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Re: The Problem with Possessions-Based Linear Weights

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  • Dean Oliver
    ... Let s first hear a good argument that the unmeasured contributions are more (more what?) than the measured contributions. Everything rests on this
    Message 1 of 42 , Mar 25, 2004
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      --- In APBR_analysis@yahoogroups.com, "dan_t_rosenbaum"
      <rosenbaum@u...> wrote:
      > So what is wrong with this approach? The problem is that there are
      > numerous contributions to successful or failed possessions for which
      > there are no statistics - a good pick, an ineffective blockout, a
      > good entry pass that leads to a score but not an assist, the
      > presence of a shot blocker that keeps his opponents from driving to
      > the hoop. One could easily argue that the unmeasured contributions
      > to successful or failed possessions are more than the measured
      > contributions, e.g. points, assists, steals, etc.

      Let's first hear a good argument that the unmeasured contributions are
      more (more what?) than the measured contributions. Everything rests
      on this statement. If unmeasured contributions are relatively
      unimportant (which I believe they are on the offensive side, not the
      defensive side), then you can use an approach like mine.

      DeanO

      Dean Oliver
      Author, Basketball on Paper
      http://www.basketballonpaper.com

      "Oliver's book provides an insightful framework for basketball. His
      approach highlights and simplifies the basic goals of team offenses
      and defenses, with an interesting description of how teamwork among
      players with different roles can be evaluated. This book is a unique
      and surprisingly practical addition to a coach's library." Dean
      Smith, Hall of Fame Basketball Coach, University of North Carolina
    • dan_t_rosenbaum
      I think wimpds has a point here. If a particular player with limited offensive skills tends to play at times when his teammates shoot more poorly (because they
      Message 42 of 42 , Mar 30, 2004
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        I think wimpds has a point here.

        If a particular player with limited offensive skills tends to play
        at times when his teammates shoot more poorly (because they are in
        essence playing 4 on 5) than their WINVAL ratings suggest they
        should, that player would end up with more offensive rebounding
        opportunities than a typical player.

        But let's suppose a guy is on the floor for 80 possessions in 40
        minutes and he drops his team's shooting percentage down 5
        percentage points (a pretty big drop). I would assume that would
        result in about three to five extra offensive rebounding
        opportunities for this player and if he collects 10 percent of those
        extra rebounds, this amounts to 0.3 to 0.5 extra offensive rebounds
        per 40 minutes. Not trivial, but also not a huge difference.

        --- In APBR_analysis@yahoogroups.com, "wimpds" <wimpds@y...> wrote:
        > But if teammates are more likely to miss shots when they play with
        you
        > than when they play with other players, that will depress your
        WinVal
        > rating, right? If this attribute is correlated with individual
        > offensive rebounding, won't it have a negative effect on the value
        of
        > the coefficent?
        >
        > On the defensive side, we only have a few variables to contribute
        > significantly to your WinVal rating. [I'd be interested in seeing
        > regressions run separately on the offensive and defensive WinVal
        > ratings.] Defensive Rebounds coefficient might be picking up
        > something more than simply rebounding ability, it could be getting
        at
        > defense somewhat more generally.
        >
        >
        >
        > --- In APBR_analysis@yahoogroups.com, "Michael Tamada"
        <tamada@o...>
        > wrote:
        > > It's a good thought, although the regression should already
        > > account for this by already measuring the impact of
        > > opponents missing shots and one's team missing shots.
        > >
        > >
        > > --MKT
        > >
        > >
        > > -----Original Message-----
        > > From: wimpds [mailto:wimpds@y...]
        > > Sent: Monday, March 29, 2004 3:13 PM
        > > To: APBR_analysis@yahoogroups.com
        > > Subject: [APBR_analysis] Re: The Problem with Possessions-Based
        Linear
        > > Weights
        > >
        > >
        > > Another thought on this subject ( though I may not be thinking
        through
        > > the regression carefully enough) is that offensive rebounds are
        > > probably correlated with having teammates missing shots while
        > > defensive rebounds are correlated with the opponent missing
        shots.
        > > This effect would seem to be even stronger if your teammates are
        more
        > > likely to miss because you're not attracting any defensive
        attention.
        > >
        > >
        > >
        > >
        > >
        > > --- In APBR_analysis@yahoogroups.com, "carlos12155"
        > > <carlosmanuel@b...> wrote:
        > > > --- In APBR_analysis@yahoogroups.com, "Mike G" <msg_53@h...>
        wrote:
        > > > > --- In APBR_analysis@yahoogroups.com, "Kevin Pelton"
        > > > > <kpelton08@h...> wrote:
        > > > > >
        > > > > > Rodman specialized in rebounding -- not offensive
        rebounding. He
        > > > > was
        > > > > > great at both ends. I don't know if I can think of someone
        who
        > > > > > specializes specifically in offensive rebounding.
        > > > >
        > > > > The original poster meant, I'm sure, that on Offense, Rodman
        did
        > > > > little more than rebound missed shots, at least by the time
        in his
        > > > > career when he was with the Bulls.
        > > > >
        > > > > Obviously, he went to the other end of the court on defense,
        and
        > did
        > > > > other things there.
        > > > >
        > > >
        > > > That was exactly my intention. It seemed to me that if
        offensive
        > > > rebounds are at some level a negative, Rodman performance
        would be the
        > > > perfect example; after all that was the only thing he did on
        offense.
        > >
        > >
        > >
        > >
        > > Yahoo! Groups Links
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