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Re: Assigning Credit to Players

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  • 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 1 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 2 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 3 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 4 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 5 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 6 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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