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Re: Assigning Credit to Players

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  • mikel_ind
    This raises the spectre of French judges, and tends to drive me to the side of those who like to say stats don t matter; only winning matters . But I will
    Message 1 of 10 , Mar 14, 2002
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      This raises the spectre of French judges, and tends to drive me to
      the side of those who like to say "stats don't matter; only winning
      matters".

      But I will endeavor to make constructive comments.

      --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
      >

      > 1. The point guard passes through the defense to a big man
      > underneath the basket for a dunk. What percentage of the credit for
      > the TEAM score should go to the passer vs. the scorer? Obviously,
      > one player gets an assist and one gets the field goal, but,
      > subjectively, should they split credit 50-50?

      The guard lobs a pass up high, the big man has to reach behind
      himself while leaping out of the gym: 120% to the big man, -20% to
      the passer.
      (Obviously, every case is different).

      > 2. A point guard passes to an unguarded mediocre shooter at the
      > perimeter who makes a jump shot. How should credit be split here?
      >
      Depends on the shot clock and a zillion other things. Who decides
      that guy is mediocre? Maybe that is his spot. Maybe he was knocking
      them down in practice. Maybe the guy needs a vote of confidence.
      Ignoring your wide-open shooter is poison to team chemistry, besides
      surrendering to the opposition at that matchup.

      > 3. On a pick and roll, the guard gets double-teamed and finds the
      > roll-guy near the basket for an open 5 ft shot.
      >
      > 4. On a pick and roll, the guard gets double-teamed and finds the
      > roll-guy popping out for a 15 ft jump shot.
      >
      > 5. On a pick and roll, the guard's man is picked off with no
      switch,
      > freeing him for an open 18 ft jump shot.

      My guts tell me success is its own reward, players get back to the
      guy that set them up, teams gel or don't gel, playing time is the
      result of good play.

      > 6. In situation 3, how do you split the credit/blame to the two
      > defenders who didn't shut down the pick and roll? Should the rest
      of
      > the team also receive blame? How much?

      How many ways could one split a hair? Further, why should one?

      ....
      > 9. A guard misses a jump shot, which is rebounded and stuck back in
      > by a teammate. How much credit goes to the two players?
      >
      > 10. A guard misses a jump shot, which is rebounded by a teammate.
      > He passes back to the guard to restart the offense, which, after
      > several passes, scores. How much credit should go to the offensive
      > rebounder?

      Now we are looking at the spectre of several "French judgments" on
      the same play.

      Sorry, I just don't get it.


      Mike Goodman
    • mikel_ind
      ... Any number from .1 to .9 might be appropriate. ... superior ... (If it s ... no great ... Passing to Bradley 30 feet away will yield no assists, so this
      Message 2 of 10 , Mar 14, 2002
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        --- In APBR_analysis@y..., "Michael K. Tamada" <tamada@o...> wrote:
        >
        > Here are my gut feel answers:
        > >
        > > 1. The point guard passes through the defense to a big man
        > > underneath ...., should they split credit 50-50?
        >
        > Passer 2/3, dunker 1/3.

        Any number from .1 to .9 might be appropriate.


        >...ideally we'd want the point guard to pass to unguarded good
        > shooters rather than unguarded mediocre shooters. It's a clearly
        superior
        > situation, and is likely to be harder for the passer to achieve.
        (If it's
        > Shawn Bradley 30 feet from the basket, getting the ball to him is
        no great
        > achievement).

        Passing to Bradley 30 feet away will yield no assists, so this credit
        is built-in.
        (Unless the clock is about to expire, and Bradley is the only guy
        open. In this case, not-passing-to-Bradley should get you yanked
        from the game.)

        > All that suggests that the passer should get more credit when
        passing to
        > the good shooter than the mediocre shooter.
        >.... So if Reggie Miller and Jeff Foster both hit open
        > 20 footers, should Reggie get less credit than Foster?
        >
        > Miller WILL make more of those baskets, so maybe it's okay to give
        him
        > less credit -- but it better not be TOO much less. Otherwise, he
        might go
        > 5-10 one night on open 20 footers, and Foster would go 4-10 ... and
        Foster
        > might be rated as having a better performance!

        Indeed, the longer you think about it, the more unimaginable the idea
        becomes. (Shouldn't Foster really be banging the boards, rather than
        hanging out at 20 feet?)

        > > 3. On a pick and roll, the guard gets double-teamed and finds the
        > > roll-guy near the basket for an open 5 ft shot.
        >
        > Guard gets 2/3 credit.
        >
        > >
        > > 4. On a pick and roll, the guard gets double-teamed and finds the
        > > roll-guy popping out for a 15 ft jump shot.
        >
        > Guard gets half credit.

        We could have concentric arcs that assign % credit in this way.
        While we're at it, install sensors under the floor, in the ball, and
        in the shoes of the players, so it is all tabulated electronically.

        This is reminiscent of some suggested extra arcs that give a team
        only 1 point inside 5 feet (or 10, or whatever), and 4 points beyond
        40 feet, etc.


        > > 5. On a pick and roll, the guard's man is picked off with no
        switch,
        > > freeing him for an open 18 ft jump shot.
        >
        > Guard gets 3/4 credit, pick-setter gets 1/4. Hmm, but how much of
        this
        > was not due to EITHER of them,

        Indeed, there are players setting picks for the pickers, acting as
        decoys, combining these actions with positioning for rebounding... My
        guess is, there are infinite possibilities you could consider.

        > but instead should be counted as a negative
        > against the defenders who failed to do their job? Should a made
        basket
        > always represent only positive things, to be apportioned among the
        > offensive players, or should we instead deduct some credits from the
        > defenders?

        Another odious can of worms: Negative statistics. Perhaps
        competition at any level should have some accounting system that adds
        up to zero. Every success is the result of some mistake.

        At a game, one is sometimes surrounded by fans who only see the
        negative aspects of the game, and a "positive" comment is "About time
        he hit that shot", or some such.

        I see the game as 90-99% beauty and excellence. Sometimes I can't
        remember the last time someone misplayed anything.

        If it were an orchestra, of course more than 90% of the notes have to
        be essentially perfect. But there is no D in music.

        What the heck were we talking about here?
      • alleyoop2
        Fascinating topic Dean. I put in my $0.02 below each item. ... Normally, I think the shooter should get most of the credit, since he has to both get open and
        Message 3 of 10 , Mar 14, 2002
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          Fascinating topic Dean. I put in my $0.02 below each item.

          --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
          >
          > I posed the following to a bunch of coaches. This group is a bit
          > tainted by my opinion, but I'll ask anyway...
          >
          > I am interested in obtaining some opinions on distributing
          > credit to players for different situations in basketball.
          >
          > For example
          >
          > 1. The point guard passes through the defense to a big man
          > underneath the basket for a dunk. What percentage of the credit for
          > the TEAM score should go to the passer vs. the scorer? Obviously,
          > one player gets an assist and one gets the field goal, but,
          > subjectively, should they split credit 50-50?

          Normally, I think the shooter should get most of the credit, since he
          has to both get open and make the shot. In this case, since the pass
          led directly to a dunk, I think it should be split more evenly. 50-
          50, or 60-40 for the shooter at worst.

          >
          > 2. A point guard passes to an unguarded mediocre shooter at the
          > perimeter who makes a jump shot. How should credit be split here?
          >

          Passing to a mediocre shooter is its own reward. He'll make a lower
          percentage so the guard will get fewer assist "credits." I would
          consider this a fairly normal assist and give 2/3 to the shooter, 1/3
          to the passer.

          > 3. On a pick and roll, the guard gets double-teamed and finds the
          > roll-guy near the basket for an open 5 ft shot.
          >
          > 4. On a pick and roll, the guard gets double-teamed and finds the
          > roll-guy popping out for a 15 ft jump shot.
          >

          Very little difference between these two IMHO, since a lot depends on
          where the roll guy decides to go. I'd go 2/3 for the shooter on each.

          > 5. On a pick and roll, the guard's man is picked off with no
          switch,
          > freeing him for an open 18 ft jump shot.
          >

          Interesting - a pick leading directly to a basket. Theoretically that
          should be worth as much as an assist. I would give as much as 1/3 of
          the credit to the screener.


          > 6. In situation 3, how do you split the credit/blame to the two
          > defenders who didn't shut down the pick and roll? Should the rest
          of
          > the team also receive blame? How much?
          >
          > 7. Same question for splitting defensive credit for #4.
          >
          > 8. Same question for splitting defensive credit for #5.
          >

          I think, if you're doing this, you have to assign -2 points to your
          defense somehow on this play. On the pick and roll it should probably
          be split among the two guys, unless one made a particularly poor play.

          > 9. A guard misses a jump shot, which is rebounded and stuck back in
          > by a teammate. How much credit goes to the two players?
          >

          Negative credit for the guard, unless you think he was passing it off
          the rim. Two credits for the rebounder - 1) regaining possession, and
          2) making the basket.

          > 10. A guard misses a jump shot, which is rebounded by a teammate.
          > He passes back to the guard to restart the offense, which, after
          > several passes, scores. How much credit should go to the offensive
          > rebounder?

          This is why I separate the regaining possession from making the
          basket above. Same negative credit to the guard.

          >
          > I'm not looking for formal studies, but rather gut feel from people
          > on these, maybe with some explanation for the answers, maybe
          > without. I recognize that coaches often don't think about
          > distributing credit this way and that it, in some ways, goes
          against
          > the spirit of the roles players should have. This is an attempt to
          > identify whether people have thought about decisions about credit
          and
          > to collect results into a report for coaches to view.
          >
          > Dean Oliver
          > Journal of Basketball Studies
          > www.rawbw.com/~deano/index.html
        • HoopStudies
          I won t say much yet on this, but I do want to introduce one aspect with regard to ... in ... off ... and ... One of the things I remember hearing about
          Message 4 of 10 , Mar 14, 2002
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            I won't say much yet on this, but I do want to introduce one aspect
            with regard to

            > > 9. A guard misses a jump shot, which is rebounded and stuck back
            in
            > > by a teammate. How much credit goes to the two players?
            > >
            >
            > Negative credit for the guard, unless you think he was passing it
            off
            > the rim. Two credits for the rebounder - 1) regaining possession,
            and
            > 2) making the basket.

            One of the things I remember hearing about Dominique Wilkins and have
            heard about Allen Iverson is that their shots are more often
            rebounded by their own team because their teammates know that they
            are going to shoot the ball. We already have put forth evidence (I
            think, I know I did the work) showing that Iverson's presence does
            help the Philly offense even though the boy sometimes can't hit the
            side of a barn with his shot.

            Just something to consider.

            DeanO
          • McKibbin, Stuart
            I m not looking for formal studies, but rather gut feel from people on these, maybe with some explanation for the answers, maybe without. 1. The point guard
            Message 5 of 10 , Mar 14, 2002
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              I'm not looking for formal studies, but rather gut feel from people
              on these, maybe with some explanation for the answers, maybe
              without.

              1. The point guard passes through the defense to a big man
              underneath the basket for a dunk. What percentage of the credit for
              the TEAM score should go to the passer vs. the scorer? Obviously,
              one player gets an assist and one gets the field goal, but,
              subjectively, should they split credit 50-50?

              If the pass is truly through the defense, that is, if the point guard had to see the opening and thread the ball at high velocity past defenders to the big man, (who then has to be able to handle the pass and not drop it) who dunks the ball without the defense being able to react then I'd give ALL of the credit to the PG. The PG made the play.

              2. A point guard passes to an unguarded mediocre shooter at the
              perimeter who makes a jump shot. How should credit be split here?

              NO credit should ever be given for making a basic pass. However, if the point guard penetrates and draws Mr. Mediocre's defender to him, and subsequently passes the ball to Mr. Mediocre who hits his wide open shot then PG should get ALL of the credit. Again, the PG made the play.


              9. A guard misses a jump shot, which is rebounded and stuck back in
              by a teammate. How much credit goes to the two players?

              I agree with others---what the hell did the guard do to earn credit? It sounds like his offensive rebounding teammate just bailed him out.

              10. A guard misses a jump shot, which is rebounded by a teammate.
              He passes back to the guard to restart the offense, which, after
              several passes, scores. How much credit should go to the offensive
              rebounder?

              No more than should be given a guy for grabbing a defensive rebound, or stealing the ball, or taking the ball out of the net. Or for that matter, to the opponent for kicking the ball out of bounds. In other words if the offensive rebound doesn't lead DIRECTLY to the basket, who cares how you got the ball?
            • dlirag
              ... back ... have ... A shot can be seen as a pass that results in one of the following things happening: 2 or 3 points are immediately scored (45% chance),
              Message 6 of 10 , Mar 29, 2002
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                --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
                > > > 9. A guard misses a jump shot, which is rebounded and stuck
                back
                > in
                > > > by a teammate. How much credit goes to the two players?
                > > >
                > >
                > > Negative credit for the guard, unless you think he was passing it
                > off
                > > the rim. Two credits for the rebounder - 1) regaining possession,
                > and
                > > 2) making the basket.
                >
                > One of the things I remember hearing about Dominique Wilkins and
                have
                > heard about Allen Iverson is that their shots are more often
                > rebounded by their own team because their teammates know that they
                > are going to shoot the ball. We already have put forth evidence (I
                > think, I know I did the work) showing that Iverson's presence does
                > help the Philly offense even though the boy sometimes can't hit the
                > side of a barn with his shot.

                A shot can be seen as a pass that results in one of the following
                things happening: 2 or 3 points are immediately scored (45% chance),
                the ball ends up in a teammate's hands (16% chance), or the ball goes
                to the opposing team (39% chance).

                Seen this way, a missed jump shot that's put back in by a teammate
                could be recast as a bad pass to a teammate who manages to score off
                this pass. Maybe one should allocate credit with this revised view of
                missed shots in mind, but I'm not yet sure.
              • HoopStudies
                ... they ... (I ... does ... the ... chance), ... goes ... This gets at what Gary Skoog did in one of James abstracts, where they assessed the expected runs
                Message 7 of 10 , Mar 29, 2002
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                  --- In APBR_analysis@y..., "dlirag" <dlirag@h...> wrote:
                  > >
                  > > One of the things I remember hearing about Dominique Wilkins and
                  > have
                  > > heard about Allen Iverson is that their shots are more often
                  > > rebounded by their own team because their teammates know that
                  they
                  > > are going to shoot the ball. We already have put forth evidence
                  (I
                  > > think, I know I did the work) showing that Iverson's presence
                  does
                  > > help the Philly offense even though the boy sometimes can't hit
                  the
                  > > side of a barn with his shot.
                  >
                  > A shot can be seen as a pass that results in one of the following
                  > things happening: 2 or 3 points are immediately scored (45%
                  chance),
                  > the ball ends up in a teammate's hands (16% chance), or the ball
                  goes
                  > to the opposing team (39% chance).

                  This gets at what Gary Skoog did in one of James' abstracts, where
                  they assessed the expected runs for every given state and assigned
                  credit/blame for transitions between those states.

                  At the point before a shot, every possession is worth about 1 pt.
                  After the shot, it could go to 2 pts with a made shot and end of
                  possession, 3 pts with a made shot and end of possession, rare cases
                  of >3 pts with or without continued possession, 0 pts with the
                  probability of an offensive rebound (expected value of 1 pt after
                  OR), 0 pts with probability of opponent getting the ball (expected
                  value of 0 after DR). In the 0 pts with offensive rebound, you
                  diminish the value of the missed shot by about 2/3 (assuming 1/3
                  chance of OR), so, using relative to the mean credit (as Skoog did),
                  the credit is -2/3 to the shooter who missed (bring expected points
                  from 1 to 1/3), 2/3 to the offensive rebounder (who brought it back
                  to 1), then 1 to the scorer (for going from 1 to 2). If this
                  methodology is carried out in detail, you could modify the shooter-
                  specific OR%, so that rather than diminishing Iverson's misses by
                  2/3, you diminish them by 1/2 if you think that half of his misses
                  are rebounded by the offense.

                  Though in this case the rebounder and scorer are the same, note that
                  there is more relative credit to the scorer (+1) than to the
                  rebounder (+2/3). This may be in conflict with what the offensive
                  rebound studies we did earlier here said, but I'd need to check.

                  Dean Oliver
                • Michael K. Tamada
                  ... [...] ... [...] This is how my model of basketball works. It can be used to generate means and standard deviations, but can even more directly be used to
                  Message 8 of 10 , Mar 29, 2002
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                    On Fri, 29 Mar 2002, HoopStudies wrote:

                    > --- In APBR_analysis@y..., "dlirag" <dlirag@h...> wrote:

                    [...]

                    > > A shot can be seen as a pass that results in one of the following
                    > > things happening: 2 or 3 points are immediately scored (45%
                    > chance),
                    > > the ball ends up in a teammate's hands (16% chance), or the ball
                    > goes
                    > > to the opposing team (39% chance).
                    >
                    > This gets at what Gary Skoog did in one of James' abstracts, where
                    > they assessed the expected runs for every given state and assigned
                    > credit/blame for transitions between those states.
                    >
                    > At the point before a shot, every possession is worth about 1 pt.
                    > After the shot, it could go to 2 pts with a made shot and end of
                    > possession, 3 pts with a made shot and end of possession, rare cases

                    [...]

                    This is how my model of basketball works. It can be used to generate
                    means and standard deviations, but can even more directly be used to
                    estimate win probabilities. The trouble is that the models make it easy
                    and tempting to assign all the credit for an action to a player, e.g. the
                    offensive rebounder gets the +2/3 that you describe, when some of the
                    credit perhaps should go to teammates who blocked out (unlikely however in
                    an offensive rebounding situation) and maybe some of the blame should go
                    to the defensive rebounder who failed to block the guy out. So this model
                    makes assignment of credit to players easy to do -- but not necessarily
                    truly accurate.

                    > Though in this case the rebounder and scorer are the same, note that
                    > there is more relative credit to the scorer (+1) than to the
                    > rebounder (+2/3). This may be in conflict with what the offensive
                    > rebound studies we did earlier here said, but I'd need to check.

                    No, scoring a field goal is clearly more valuable than grabbing an
                    offensive rebound, even when the loss of possession is taken into account.
                    Missing a field goal is the act that is approximately equal to an
                    offensive rebound.


                    --MKT
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