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A womans perspective on offensive rebounds

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  • John Maxwell
    Okay, maybe not a woman s perspective, but a perspective on the women s game Over the past week or two, I ve been trying to log all of the offensive rebounds
    Message 1 of 2 , Dec 10, 2001
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      Okay, maybe not a woman's perspective, but a perspective on the women's game

      Over the past week or two, I've been trying to log all of the offensive
      rebounds from last season in the WNBA to determine the importance of an
      offensive rebound to a team's offense. When I'm done, I'll have team and
      individual figures as well, but for now I thought I'd share what I've got on
      a league-wide level.

      So far I've logged 2,012 of 5,056 offensive rebounds. My xl sheets note who
      grabbed the rebound, if the player that grabbed the rebound took the
      subsequent shot or turned the ball over, the kind of shot (two-pointer,
      three-pointer, free throws), the number of points derived from the offensive
      rebound, if the player's teammates took the subsequent shot or turned the
      ball over, the kind of shot, and the number of points derived from the
      offensive rebound.

      Some things that aren't logged -- Whether or not the player that grabbed the
      offensive rebound put the shot back up immediately or took the shot later in
      the possession as part of the offense, the kind of shot that was rebounded,
      the shot clock at the time of the rebound, if the player who grabbed the
      offensive rebound assisted on her teammate's subsequent field goal. I'm sure
      there are other things that I can't think of that might have been worth
      looking into, but that's what I can think of off the top of my head. If
      anybody has any suggestions as to if any of these things or other items
      should be logged, I can look into it when I go back through to check my work

      Dean, I'm particularly interested to see how this information might alter
      the credit given for an offensive rebound in your formulas.

      So with 40 percent of the rebounds logged, here's what I've found.

      In the WNBA . . .

      57.2 percent of activity following the offensive rebound is generated by the
      offensive rebounder. The offensive rebounder shoots the ball on 78 percent
      of the activity that she generates, gets fouled and goes to the free throw
      line on 13 percent of the activity she generates and turns the ball over the
      remaining 9 percent of the time.

      The remaining 42.8 percent of the activity following the offensive rebound
      is generated by the offensive rebounder's teammates. Her teammates shoot the
      ball on 75 percent of the activity they generate, get fouled and go to the
      free throw line on 10 percent of the activity they generate and turn the
      ball over 15 percent of the time.

      ----------------- Poss*--- FGA --- FTA --- TO -------3GA
      Orebounder --- 1150 --- 78% ---- 13% ---- 9% --------4%
      Teammates ---- 856 ---- 75% ---- 10% --- 15% ------14%

      I threw in the percentage of three-point field goal attempts there at the
      end.

      Success Rates
      Offensive rebounders are successful on 48.1 percent of their field goal
      attempts, 23.4 percent of their three-point field goal attempts and 70.7
      percent of their free throws. An offensive rebounders teammates are
      successful on 41.6 percent of their field goal attempts, 36.8 percent of
      their three-point field goal attempts and 68.0 percent of their free throw
      attempts.

      Percentages
      -------------------- FG ----- 3G ----- FT ---- Pts/Poss
      Orebounder ----- 48.1 --- 23.4 --- 70.7 ------ 0.944
      Teammates ----- 41.6 ---- 36.8 --- 68.0 ----- 0.833
      Combined ------- 45.4 --- 33.9 --- 69.7 ------ 0.897

      Lg Avg ---------- 41.1 ---- 33.6 --- 74.1 ----- 0.815
      Lg Avg-Oreb --- 40.5 ---- 33.5 --- 74.8 ----- 0.805

      Lg Avg stands for the overall league average. Lg Avg-Oreb stands for the
      league average minus the possessions affected by an offensive rebound - sort
      of a "First Shot" percentage. Since I haven't logged all the rebounds, I
      just assumed the same percentages for the remaining 3000 offensive rebounds
      to get a ballpark figure.

      Pts/Poss stands for points per possession. I counted each offensive rebound
      as a new possessions despite the fact that most of us don't consider it to
      be one since the ball never changes hands. I did this because it was the
      only way I could compare apples to apples with regards to how I was logging
      the offensive rebound data.

      Thoughts:
      Much of the data backs up what you might guess about the importance of an
      offensive rebound.

      Free Throw Percentages - the free throw percentages following an offensive
      rebound are lower than the league average because taller players are the
      ones grabbing the offensive rebounds, and taller players are, traditionally,
      the players who don't shoot as well from the free throw line. Dawn Staley is
      the WNBA's career free throw percentage leader, but she only grabbed 11
      offensive rebounds last season.

      The offensive rebounder hits a higher percentage of her shots than the
      league average due to her proximity to the basket. She also takes vastly
      fewer three-point field goal attempts for this same reason.

      The offensive rebounder's teammates hit a higher percentage of three point
      field goal attempts because everybody's attention is diverted towards the
      basket.

      Teams score more points per possession off of offensive rebounds than "First
      Shot" possessions, even those possessions that are affected by the offensive
      rebounder's teammates, although not by as much.

      Here are the hard numbers
      ----------------- Poss --- FG-FGA -- 3G-3GA -- FT-FTA ---- Pts -- TO
      Orebounder -- 1150 --- 430-894 ----- 11-47 ---- 215-304 --- 1086 -- 107
      Teammates ---- 856 --- 266-639 ----- 64-174 --- 117-172 ---- 713 -- 132
      Combined ---- 2006* -- 696-1533 --- 75-221 --- 332-476 -- 1799 --- 239

      *The possessions don't add up to the total number of offensive rebounds
      because a handful of offensive rebounds were credited right at the end of
      halves or the game where no additional shots were taken.

      That's all for now.

      John Maxwell
      Director of Public Relations
      Charlotte Sting
    • HoopStudies
      Great information being provided here and by Stuart. How do I use this info? It s explained somewhat here:
      Message 2 of 2 , Dec 11, 2001
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        Great information being provided here and by Stuart.

        How do I use this info? It's explained somewhat here:

        http://www.rawbw.com/~deano/articles/JordanvsOlaj.html

        My formula has changed slightly from then (that was written in '96)
        and the theory has advanced. But at a conceptual level, here is what
        goes on:

        Offensive rebounds are an indirect contributor to a scoring
        possession, somewhat like an assist, though an assist is even more
        direct. An offensive rebound contributes to a scoring possession by
        giving the offense another _chance_ to score, not a score itself.
        For example, I'm looking at a recent Blazer-Sonic game (where
        Portland won easily) where Portland shot 45/81 from the field and had
        12 offensive rebounds. If you look only at how Portland did without
        offensive rebounds, they scored on 54% of their "possessions" (called
        a "Play %") = [FGM + (1- (1-FT%)^2)*0.4*FTA ] / [FGA + 0.4 * FTA +
        TO], where FGM = 45, FGA = 81, FTA = 28, TO = 11, FTM = 20 (ft% =
        0.714). If you look at how Portland did _with_ offensive rebounds,
        they scored on 61% of their possessions ("floor %") FGM + (1- (1-FT%)
        ^2)*0.4*FTA ] / [FGA - OR + 0.4 * FTA + TO]. Basically, those 12
        offensive rebounds turned into 6 new scoring possessions (~12 *
        0.536, though my accounting says that some are probably duplicates).
        I disperse that credit to individual scoring possessions according to
        their offensive rebounds. I remove that credit evenly from all
        player scoring possessions according to the assumption that they all
        evenly benefit from team offensive rebounds.

        Where all this detailed accounting from John and Stuart helps is in a
        few areas. First, that play % is suggested to be a little bit higher
        after offensive rebounds. If I adjust that in the formula, it gives
        more credit to offensive rebounders than I currently give. Second, I
        have assumed in my accounting even distribution after the offensive
        rebound -- equal likelihood that anyone on the floor could score.
        That definitely seems to not be the case from the detailed work.
        This affects two things. It means that offensive rebounders are less
        likely to have their made shots assisted on -- because more of their
        made shots are after OR's, which are not assisted on. That helps
        them. Second, I give half credit to the offensive rebounder and half
        to "the rest of the team" on scoring possessions created by an
        offensive rebound. (The ORFIG on the website said 0.1, but I worked
        out the theory better to say that 0.5 works best in combination with
        other changes I made.) This detailed work from John and Stuart is
        suggesting that the "rest of the team" typically consists of that
        offensive rebounder sticking it back. I need to work through the
        theory to see whether I need to change that half credit to something
        else. I don't think so, but I don't know.

        Again, outstanding work you guys are doing. At some time in the not
        too distant past, I felt like there was a serious lack of data to
        help do detailed analysis. This is changing that. Now the
        limitation is time to do the analysis.

        Dean Oliver
        Journal of Basketball Studies


        --- In APBR_analysis@y..., "John Maxwell" <John.Maxwell@C...> wrote:
        > Okay, maybe not a woman's perspective, but a perspective on the
        women's game
        >
        > Over the past week or two, I've been trying to log all of the
        offensive
        > rebounds from last season in the WNBA to determine the importance
        of an
        > offensive rebound to a team's offense. When I'm done, I'll have
        team and
        > individual figures as well, but for now I thought I'd share what
        I've got on
        > a league-wide level.
        >
        > So far I've logged 2,012 of 5,056 offensive rebounds. My xl sheets
        note who
        > grabbed the rebound, if the player that grabbed the rebound took the
        > subsequent shot or turned the ball over, the kind of shot (two-
        pointer,
        > three-pointer, free throws), the number of points derived from the
        offensive
        > rebound, if the player's teammates took the subsequent shot or
        turned the
        > ball over, the kind of shot, and the number of points derived from
        the
        > offensive rebound.
        >
        > Some things that aren't logged -- Whether or not the player that
        grabbed the
        > offensive rebound put the shot back up immediately or took the shot
        later in
        > the possession as part of the offense, the kind of shot that was
        rebounded,
        > the shot clock at the time of the rebound, if the player who
        grabbed the
        > offensive rebound assisted on her teammate's subsequent field goal.
        I'm sure
        > there are other things that I can't think of that might have been
        worth
        > looking into, but that's what I can think of off the top of my
        head. If
        > anybody has any suggestions as to if any of these things or other
        items
        > should be logged, I can look into it when I go back through to
        check my work
        >
        > Dean, I'm particularly interested to see how this information might
        alter
        > the credit given for an offensive rebound in your formulas.
        >
        > So with 40 percent of the rebounds logged, here's what I've found.
        >
        > In the WNBA . . .
        >
        > 57.2 percent of activity following the offensive rebound is
        generated by the
        > offensive rebounder. The offensive rebounder shoots the ball on 78
        percent
        > of the activity that she generates, gets fouled and goes to the
        free throw
        > line on 13 percent of the activity she generates and turns the ball
        over the
        > remaining 9 percent of the time.
        >
        > The remaining 42.8 percent of the activity following the offensive
        rebound
        > is generated by the offensive rebounder's teammates. Her teammates
        shoot the
        > ball on 75 percent of the activity they generate, get fouled and go
        to the
        > free throw line on 10 percent of the activity they generate and
        turn the
        > ball over 15 percent of the time.
        >
        > ----------------- Poss*--- FGA --- FTA --- TO -------3GA
        > Orebounder --- 1150 --- 78% ---- 13% ---- 9% --------4%
        > Teammates ---- 856 ---- 75% ---- 10% --- 15% ------14%
        >
        > I threw in the percentage of three-point field goal attempts there
        at the
        > end.
        >
        > Success Rates
        > Offensive rebounders are successful on 48.1 percent of their field
        goal
        > attempts, 23.4 percent of their three-point field goal attempts and
        70.7
        > percent of their free throws. An offensive rebounders teammates are
        > successful on 41.6 percent of their field goal attempts, 36.8
        percent of
        > their three-point field goal attempts and 68.0 percent of their
        free throw
        > attempts.
        >
        > Percentages
        > -------------------- FG ----- 3G ----- FT ---- Pts/Poss
        > Orebounder ----- 48.1 --- 23.4 --- 70.7 ------ 0.944
        > Teammates ----- 41.6 ---- 36.8 --- 68.0 ----- 0.833
        > Combined ------- 45.4 --- 33.9 --- 69.7 ------ 0.897
        >
        > Lg Avg ---------- 41.1 ---- 33.6 --- 74.1 ----- 0.815
        > Lg Avg-Oreb --- 40.5 ---- 33.5 --- 74.8 ----- 0.805
        >
        > Lg Avg stands for the overall league average. Lg Avg-Oreb stands
        for the
        > league average minus the possessions affected by an offensive
        rebound - sort
        > of a "First Shot" percentage. Since I haven't logged all the
        rebounds, I
        > just assumed the same percentages for the remaining 3000 offensive
        rebounds
        > to get a ballpark figure.
        >
        > Pts/Poss stands for points per possession. I counted each offensive
        rebound
        > as a new possessions despite the fact that most of us don't
        consider it to
        > be one since the ball never changes hands. I did this because it
        was the
        > only way I could compare apples to apples with regards to how I was
        logging
        > the offensive rebound data.
        >
        > Thoughts:
        > Much of the data backs up what you might guess about the importance
        of an
        > offensive rebound.
        >
        > Free Throw Percentages - the free throw percentages following an
        offensive
        > rebound are lower than the league average because taller players
        are the
        > ones grabbing the offensive rebounds, and taller players are,
        traditionally,
        > the players who don't shoot as well from the free throw line. Dawn
        Staley is
        > the WNBA's career free throw percentage leader, but she only
        grabbed 11
        > offensive rebounds last season.
        >
        > The offensive rebounder hits a higher percentage of her shots than
        the
        > league average due to her proximity to the basket. She also takes
        vastly
        > fewer three-point field goal attempts for this same reason.
        >
        > The offensive rebounder's teammates hit a higher percentage of
        three point
        > field goal attempts because everybody's attention is diverted
        towards the
        > basket.
        >
        > Teams score more points per possession off of offensive rebounds
        than "First
        > Shot" possessions, even those possessions that are affected by the
        offensive
        > rebounder's teammates, although not by as much.
        >
        > Here are the hard numbers
        > ----------------- Poss --- FG-FGA -- 3G-3GA -- FT-FTA ---- Pts -- TO
        > Orebounder -- 1150 --- 430-894 ----- 11-47 ---- 215-304 --- 1086 --
        107
        > Teammates ---- 856 --- 266-639 ----- 64-174 --- 117-172 ---- 713 --
        132
        > Combined ---- 2006* -- 696-1533 --- 75-221 --- 332-476 -- 1799 ---
        239
        >
        > *The possessions don't add up to the total number of offensive
        rebounds
        > because a handful of offensive rebounds were credited right at the
        end of
        > halves or the game where no additional shots were taken.
        >
        > That's all for now.
        >
        > John Maxwell
        > Director of Public Relations
        > Charlotte Sting
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