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Re: My Version 2 of WINVAL

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  • Mike G
    ... attempts... ... Part of the value of a 2-pt attempt is that fouls are created. Part of this value is in the high-% FT that ensue; and part is that fouls
    Message 1 of 5 , Mar 1, 2004
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      --- In APBR_analysis@yahoogroups.com, igor eduardo küpfer
      <edkupfer@r...> wrote:
      > ... Common Wisdom has it that 3 pointers generate
      > more offensive rebounds, which could add to the value of the long
      attempts...
      >

      Part of the value of a "2-pt attempt" is that fouls are created.
      Part of this value is in the high-% FT that ensue; and part is that
      fouls can weaken the opponent for the remainder of the game.

      However, a study that measures blocks of time when certain players
      are in the game will not pick up an effect that removes a player
      from the lineup. By definition, that effect is shifted to a
      later 'time block'.


      > Is there some double counting going on here? A steal is always a
      turnover,
      > but a turnover is not always a steal. Is it possible to isolate
      the types of
      > turnovers (steals, bad pass, OFF foul, etc.) in this analysis?

      My impression is that Dan gets it right to conjecture that each
      Recorded steal is associated with other disruptions by the defense.
      Conversely, a turnover may not be 'all that bad' if it's equivalent
      to a desperation shot; i.e., a desperation clock-fighting pass.

      > .. My opinion, backed tentatively by
      > the data I've looked at, is that defensive rebounds have less
      marginal value
      > than offensive rebounds. That is, an individual player's defensive
      rebound
      > adds less to his team's defensive rebounding percentage than that
      player's
      > offensive rebound adds to his team's offensive rebounding
      percentage...

      Again, each defensive rebound that gets recorded may represent
      several 'assisted rebounds', in which there are several defensive
      players boxing out and otherwise making it easier for one player to
      get the rebound. 3 players may work together to gather 20 rebounds;
      how they officially divide them up for credit, is immaterial to the
      success of the team.

      So each DR recorded may represent several "partial" DR, if such
      things were recorded.
    • John Hollinger
      My research in the 2002 Prospectus showed just the opposite -- that a 3-pointer had LESS chance of being rebounded than a two-point shot. Which makes sense,
      Message 2 of 5 , Mar 1, 2004
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        My research in the 2002 Prospectus showed just the opposite -- that a
        3-pointer had LESS chance of being rebounded than a two-point shot.
        Which makes sense, because coaches are fond of saying the most
        dangerous rebounder is the shooter, and on a 3-pointer the shooter is
        too far away to get most rebounds.



        --- In APBR_analysis@yahoogroups.com, igor eduardo küpfer
        <edkupfer@r...> wrote:
        > From: "dan_t_rosenbaum" <rosenbaum@u...>
        > To: <APBR_analysis@yahoogroups.com>
        > Sent: Sunday, February 29, 2004 1:45 AM
        > Subject: [APBR_analysis] My Version 2 of WINVAL
        >
        >
        > > This version is possessions-based (and thus accounts for pace) and
        > > also includes offensive and defensive ratings.
        > >
        > > In order to make it easier to read, I just included it and my
        > > comments on it on a web-page that I created. Here is the link.
        > >
        > > http://www.uncg.edu/bae/people/rosenbaum/NBA/winval1.htm
        > >
        > > (This thing has almost turned into a mini-paper.)
        > >
        >
        > "Mini"? :-)
        >
        > Great stuff, Dan. It will take me a few days to digest the whole
        thing. A
        > couple of comments in passing:
        >
        > * <quote>
        > Null Hypothesis: the cost of two point FGA is the same as the cost
        of three
        > point FGA
        >
        > The null hypothesis is soundly rejected with three point FGA having
        a lower
        > cost, even after accounting for points produced and free throw
        attempts
        > generated.
        > </q>
        >
        > Would it be asking too much to try this one again, this time
        including
        > rebounds in the accounting? Common Wisdom has it that 3 pointers
        generate
        > more offensive rebounds, which could add to the value of the long
        attempts.
        > (I'm aware that DeanO disputes CW in his book, and I accept his
        conclusion
        > that 3 misses are no more likely to be offensively rebounded than 2
        misses.
        > Independent confirmation would be very nice, however.)
        >
        > * <quote>
        > Null Hypothesis: steals and turnovers have the same value, but
        opposite
        > signs
        >
        > It is a fairly close call, but the null hypothesis is rejected. It
        appears
        > that steals help teams more than turnovers hurt teams. This could
        be because
        > guys who get steals disrupt offenses in other ways that are not
        picked up in
        > traditional statistics.
        > </q>
        >
        > Is there some double counting going on here? A steal is always a
        turnover,
        > but a turnover is not always a steal. Is it possible to isolate the
        types of
        > turnovers (steals, bad pass, OFF foul, etc.) in this analysis?
        >
        > * <quote>
        > Null Hypothesis: offensive and defensive rebounds have the same
        value
        >
        > There is no evidence to reject this hypothesis. Thus, even though
        these two
        > regressions have higher coefficients for defensive rebounds (versus
        > offensive rebounds), there really is no evidence to conclude
        statistically
        > that the value of defensive rebounds is higher than that of
        offensive
        > rebounds. That said, it is very, very difficult to draw the
        conclusion from
        > these data that offensive rebounds should be valued higher than
        defensive
        > rebounds, as is often argued.
        > </q>
        >
        > Still a topic of great interest for me. My opinion, backed
        tentatively by
        > the data I've looked at, is that defensive rebounds have less
        marginal value
        > than offensive rebounds. That is, an individual player's defensive
        rebound
        > adds less to his team's defensive rebounding percentage than that
        player's
        > offensive rebound adds to his team's offensive rebounding
        percentage. I'm
        > not sure if you address this: it could be that DRebs and ORebs add
        the same
        > amount to a team's production, while at the same time saying each
        _player's_
        > O and D rebounds have a different value.
        >
        >
        >
        >
        > --
        > cheers,
        > ed
      • Mike G
        ... that a ... shot. ... is ... This platitude surely predates the 3-point shot. And the danger in a player getting a rebound may lie more in what he ll do
        Message 3 of 5 , Mar 2, 2004
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          --- In APBR_analysis@yahoogroups.com, "John Hollinger"
          <alleyoop2@y...> wrote:
          > My research in the 2002 Prospectus showed just the opposite --
          that a
          > 3-pointer had LESS chance of being rebounded than a two-point
          shot.
          > Which makes sense, because coaches are fond of saying the most
          > dangerous rebounder is the shooter, and on a 3-pointer the shooter
          is
          > too far away to get most rebounds.

          This platitude surely predates the 3-point shot. And the "danger"
          in a player getting a rebound may lie more in what he'll do with it,
          than in the chances of his getting it.

          So given that a missed 3 is no more likely (or less likely) to be
          rebounded offensively, what accounts for the difference detected by
          Dr. Dan ?

          What about the missed shot that goes out of bounds? Probably more
          likely on a 3 than on a 2. Does the defense get a rebound? No, but
          effectively it's the same. Do they then get a fast break
          opportunity? No.

          So teams that shoot a lot of 3's may have relatively fewer fast
          breaks run against them. Yet they may have relatively more
          offensive rebounds. For both reasons, the outside-shooting team
          gains a cushion against a bigger/stronger opponent.

          This brings up the effect of "difference in team style". For a team
          without inside scoring, it does make sense to shoot more long
          shots. Forcing the ball inside makes the offense less efficient.

          Meanwhile, it's possible for an inside-efficient team to be even
          more efficient when shooting the 3. A mediocre 3-pt shooter can be
          a lot better when he's wide open all day, due to doubling inside.

          Smart coaches and teams take what is given them, most of the time.
          For the past several years (since before the shortened-arc era of
          the mid '90s), 3-pt shooting is (league-wide) more efficient than 2-
          pt and FT combined.




          >
          >
          >
          > --- In APBR_analysis@yahoogroups.com, igor eduardo küpfer
          > <edkupfer@r...> wrote:
          > > From: "dan_t_rosenbaum" <rosenbaum@u...>
          > > * <quote>
          > > Null Hypothesis: the cost of two point FGA is the same as the
          cost
          > of three
          > > point FGA
          > >
          > > The null hypothesis is soundly rejected with three point FGA
          having
          > a lower
          > > cost, even after accounting for points produced and free throw
          > attempts
          > > generated.
          > > </q>
          > >
          > > Would it be asking too much to try this one again, this time
          > including
          > > rebounds in the accounting? Common Wisdom has it that 3 pointers
          > generate
          > > more offensive rebounds, which could add to the value of the
          long
          > attempts.
          > > (I'm aware that DeanO disputes CW in his book, and I accept his
          > conclusion
          > > that 3 misses are no more likely to be offensively rebounded
          than 2
          > misses.
          > > Independent confirmation would be very nice, however.)
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