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Re: Similarity Scores

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  • msg_53@hotmail.com
    ... seems ... I operate under the assumption that points and rebounds are equally important as contributions; so are steals and blocks, but almost everyone
    Message 1 of 16 , Sep 16, 2001
      --- In APBR_analysis@y..., deano@t... wrote:
      >..... a reason not to use Euclidean distance -- it
      > weights big differences too much. At least that is the subjective
      > opinion a lot of times. It's the old argument between standard
      > deviation and mean absolute difference -- the first weights big
      > differences a lot but is mathematically easier, but the second
      seems
      > to reflect more of what we want.

      I operate under the assumption that points and rebounds are equally
      important as contributions; so are steals and blocks, but almost
      everyone gets fewer than 2-3 of these, so it seems fair to weigh them
      less. Taking the standard deviation from the mean gives you the
      burden of assigning a weight to the statistical category. I avoid
      this by presuming that bigger numbers implies bigger weights. That
      is, scoring is and should be more important than, say, steals.
      (I did reduce the 'difference' factor by taking their square roots.)

      > The similarity scores, as James did
      > them and as I modified them, fit into the mean absolute difference
      > category. In Mike's categories, then, this implies that there is
      > likely one very big difference between Jordan's numbers and
      everyone
      > else (probably scoring average) -- that gets emphasized, making him
      > the most unique player. I'd like to take a stab at career
      similarity
      > scores using the approach I've outlined to see whether it id's
      Jordan
      > as most unique, too.
      >
      > MikeG -- While I like the comparisons you did, there are 2 comments
      I
      > would make:
      >
      > 1. I'd like to see some non-standardized comparisons. I do like
      the
      > standardized because they make some sense, but I think
      > non-standardized will also tell a story.

      Dean, you could do raw averages, but players from the 60s would only
      compare to players in the 60s. Actually, a great rebounder in the
      90s would seem to compare to an average rebounder in the 60s, for
      example.
      I don't have a ready database of raw averages.

      > 2. You really need some comparison of shooting percentages and
      > turnovers. It really caught my eye with the Duncan-Kareem
      > comparison. I see some similarity between these two, but there are
      > big differences in offensive efficiency. Kareem was nearly
      > unstoppable offensively - my floor%'s and offensive efficiencies
      > reflect that. Duncan is very stoppable, his offensive rating and
      > floor percentage blending in to be about average. Kareem fell to
      > average offensively only in his last year. (I also don't think
      that
      > Kareem was the defensive force that Duncan is, but my memories are
      > biased by the Kareem post-'80, when he wasn't as good as he was
      when
      > younger.)
      >
      > Dean Oliver
      > Journal of Basketball Studies

      Shooting percentages are part of what determines my standardized
      scoring rate, along with game pace (defined as points allowed). I
      only did career totals, so Kareem's incredibly long career has been
      smoothed over, and his very dominant early seasons are not truly
      reflected. Maybe Duncan has peaked, and his career averages really
      won't rank close to Kareem's.
      Further, Duncan's offensive numbers, in my system, get a big boost
      from his being on a great defensive team. You have to agree his
      offensive strength is way above average on his team. In other words,
      the go-to guy on the championship Spurs is going to rate favorably to
      the go-to guy on the champion Bucks from 30 years before, in my
      system.

      Mike Goodman
      >
      >
      > > > > >
    • Dean Oliver
      ... only ... I think this is what I was interested in. I was curious who from today would fit in the 60 s. Or, more interestingly, who from the 70 s might
      Message 2 of 16 , Sep 17, 2001
        --- In APBR_analysis@y..., msg_53@h... wrote:
        > > 1. I'd like to see some non-standardized comparisons. I do like
        > the
        > > standardized because they make some sense, but I think
        > > non-standardized will also tell a story.
        >
        > Dean, you could do raw averages, but players from the 60s would
        only
        > compare to players in the 60s. Actually, a great rebounder in the
        > 90s would seem to compare to an average rebounder in the 60s, for
        > example.
        > I don't have a ready database of raw averages.
        >

        I think this is what I was interested in. I was curious who from
        today would fit in the '60's. Or, more interestingly, who from the
        '70's might fit in today's game. Are West's raw #'s similar to
        Iverson's or to Richmond's? What happens in baseball is that
        outstanding players tend to be dissimilar to other players in their
        era, but similar to outstanding players of other eras. I have doubt
        that this would happen in basketball, using raw #'s, because of the
        style change. You seem to be saying the same thing.

        (I didn't realize that you don't have a db of raw#'s.)

        > > 2. You really need some comparison of shooting percentages and
        > > turnovers. It really caught my eye with the Duncan-Kareem
        > > comparison. I see some similarity between these two, but there
        are
        > > big differences in offensive efficiency. Kareem was nearly
        > > unstoppable offensively - my floor%'s and offensive efficiencies
        > > reflect that. Duncan is very stoppable, his offensive rating and
        > > floor percentage blending in to be about average. Kareem fell to
        > > average offensively only in his last year. (I also don't think
        > that
        > > Kareem was the defensive force that Duncan is, but my memories
        are
        > > biased by the Kareem post-'80, when he wasn't as good as he was
        > when
        > > younger.)
        >
        > Shooting percentages are part of what determines my standardized
        > scoring rate, along with game pace (defined as points allowed). I
        > only did career totals, so Kareem's incredibly long career has been
        > smoothed over, and his very dominant early seasons are not truly
        > reflected.

        One of my personal quibbles with all the tendex-like rating systems
        out there is there is that they do combine offensive with defensive
        contributions. There is a big difference in my mind between Moses
        Malone, who was an offensive force, and Hakeem Olajuwon, who has been
        dominant defensively. Both were good in the other thing, but
        dominant in just one. Kareem was dominant offensively (and probably
        defensively) early on. Duncan has been dominant defensively, not
        offensively. (Duncan appears to have more of the competitive fight
        than Kareem, but, again, I missed the early Kareem.)

        > Maybe Duncan has peaked, and his career averages really
        > won't rank close to Kareem's.

        I don't think I'd say that Duncan's peaked. He's been pretty
        remarkably consistent since entering the league. Maybe it's only
        remarkable that he stayed in school long enough to actually be ready
        for the league when entering.

        > Further, Duncan's offensive numbers, in my system, get a big boost
        > from his being on a great defensive team. You have to agree his
        > offensive strength is way above average on his team.

        Depending on how you define "average", but, yeah, Duncan looks better
        offensively than he really is because he plays on a great defensive
        team. (He would make most teams better defensively, too.)

        > Personally, I don't ever consider 'position' to be a quantifiable
        > statistic.

        James defined numbers to positions for defensive purposes (a
        shortstop is much more valuable to a defense than a 1st baseman, for
        example). That might be necessary for some of the older guys because
        defensive stats really don't exist in the '60's and early '70's. But
        we can probably still assume that a center was the most important
        defensive player back then, as he is now. This gets adequately
        reflected in blocks, steals, and defensive boards, but you do need
        those #'s.

        > assist from a center is exactly as important as an assist from a
        > guard.

        Only a minor point here -- this is not precisely true (though
        probably true enough for government work). Assists from guards tend
        to be more valuable. This is because they often have to make the
        tougher pass than big men. The weight on an assist is proportional
        to the expected FG% of the guy he passes to. Historically, big men
        have had higher FG% than guards -- hence their assists are weighted
        less. (The assists of the best shooting player on a team are less
        valuable than the assists of the guys getting him the ball.) This
        has changed with the 3 pt shot, but it's a conversion from FG% to
        effective FG%...

        Dean Oliver
        Journal of Basketball Studies
      • Mike Goodman
        ... My raw totals and per-game averages are contained in my season files, along with team totals and averages for that season. My composite lists only have
        Message 3 of 16 , Sep 18, 2001
          --- In APBR_analysis@y..., "Dean Oliver" <deano@t...> wrote:
          > (I didn't realize that you don't have a db of raw#'s.)
          >
          My raw totals and per-game averages are contained in my 'season'
          files, along with team totals and averages for that season. My
          composite lists only have the 'standardized' rates. From those
          rates, I can generate 'equivalent totals'. For 'average'
          scoring/rebounding teams, these would be equal to raw season totals.

          >
          > One of my personal quibbles with all the tendex-like rating systems
          > out there is there is that they do combine offensive with defensive
          > contributions. There is a big difference in my mind between Moses
          > Malone, who was an offensive force, and Hakeem Olajuwon, who has
          been
          > dominant defensively. Both were good in the other thing, but
          > dominant in just one. Kareem was dominant offensively (and
          probably
          > defensively) early on. Duncan has been dominant defensively, not
          > offensively. (Duncan appears to have more of the competitive fight
          > than Kareem, but, again, I missed the early Kareem.)

          I get your point, Dean, but your examples don't seem the clearest.
          Olajuwan is better than Malone because he has all the offense Malone
          had PLUS defense. Never seen the Dream shake?
          Duncan has virtually all the offense Kareem had, averaged over their
          careers, according to my numbers. Kareem did maintain a great
          shooting pct., but Duncan plays in an era of universally-tough D.

          > I don't think I'd say that Duncan's peaked. He's been pretty
          > remarkably consistent since entering the league. Maybe it's only
          > remarkable that he stayed in school long enough to actually be
          ready
          > for the league when entering.

          Some guys enter the league at full strength: Wilt, Oscar, Kareem,
          Robinson, never improved beyond their first 3 years. Others start as
          near- superstars, then several years along suddenly shift into true
          superstar mode: Magic, Bird, Olajuwon, ...

          >
          > Depending on how you define "average", but, yeah, Duncan looks
          better
          > offensively than he really is because he plays on a great defensive
          > team. (He would make most teams better defensively, too.)

          Don't know how a guy 'looks better than he really is', DeanO.

          >Assists from guards tend
          > to be more valuable. This is because they often have to make the
          > tougher pass than big men. The weight on an assist is proportional
          > to the expected FG% of the guy he passes to. Historically, big men
          > have had higher FG% than guards -- hence their assists are weighted
          > less. (The assists of the best shooting player on a team are less
          > valuable than the assists of the guys getting him the ball.) This
          > has changed with the 3 pt shot, but it's a conversion from FG% to
          > effective FG%...
          >
          > Dean Oliver
          > Journal of Basketball Studies

          This is fun, splitting hairs!
          If your center kicks out 3 nice passes to guards, who only hit one of
          the 3 shots, the center only gets one assist.
          The guard can make 3 nice passes inside, 2 of which may be converted,
          so he gets 2 assists.
          So an equally valid argument is that assists from guards
          are 'easier', and assists from centers are 'undercounted'.
          I say they are equal.

          Perhaps more to the issue, evaluate which players make those
          practical passes which may or may not get them an assist, versus
          those who will not give up the ball unless it gets them an assist. I
          can't discern the 2 types from the statistics, but I know it when I
          see it. (It might be partly discernible in that old assist/turnover
          ratio.)


          Mike Goodman
        • Dean Oliver
          ... systems ... defensive ... fight ... Olajuwon was very solid offensively (not stellar, like Kareem) -- I didn t mean to imply otherwise. Malone was just
          Message 4 of 16 , Sep 18, 2001
            --- In APBR_analysis@y..., "Mike Goodman" <msg_53@h...> wrote:
            > > One of my personal quibbles with all the tendex-like rating
            systems
            > > out there is there is that they do combine offensive with
            defensive
            > > contributions. There is a big difference in my mind between Moses
            > > Malone, who was an offensive force, and Hakeem Olajuwon, who has
            > been
            > > dominant defensively. Both were good in the other thing, but
            > > dominant in just one. Kareem was dominant offensively (and
            > probably
            > > defensively) early on. Duncan has been dominant defensively, not
            > > offensively. (Duncan appears to have more of the competitive
            fight
            > > than Kareem, but, again, I missed the early Kareem.)
            >
            > I get your point, Dean, but your examples don't seem the clearest.
            > Olajuwan is better than Malone because he has all the offense Malone
            > had PLUS defense. Never seen the Dream shake?
            > Duncan has virtually all the offense Kareem had, averaged over their
            > careers, according to my numbers. Kareem did maintain a great
            > shooting pct., but Duncan plays in an era of universally-tough D.

            Olajuwon was very solid offensively (not stellar, like Kareem) -- I
            didn't mean to imply otherwise. Malone was just the epitome of a good
            offensive center who wasn't that good defensively. Rik Smits is
            another example of the poor defensive type who can score (not as well
            as Olajuwon/Moses). Olajuwon is very DISSIMILAR to these guys because
            he is much better defensively. Similarity is all I'm trying to
            capture, not quality.

            I looked at Duncan's offensive #'s last night and his offensive rating
            has been between about 104 and 108 since entering the league, when
            average offensive ratings have been between about 100 and 103. He's a
            little more efficient than average. My recollection of Kareem's #'s
            were about 115 in the early '80s, when average was about 106-108 --
            relatively higher than Duncan's. Again, these two players just don't
            seem very SIMILAR to me. I would think of David Robinson as more
            similar to Kareem. Or possibly Olajuwon. Probably Wilt. Not
            Russell.

            > >
            > > Depending on how you define "average", but, yeah, Duncan looks
            > better
            > > offensively than he really is because he plays on a great
            defensive
            > > team. (He would make most teams better defensively, too.)
            >
            > Don't know how a guy 'looks better than he really is', DeanO.
            >

            Another way of saying that the hype on Duncan has been a little
            extreme. Put him on the Hawks last year and, while he's better than
            Mutombo offensively, the team still wouldn't have scored much. They
            would have been pretty close to as good defensively as they were with
            Mutombo (or better), but they wouldn't be an offensive threat. I
            don't think Kareem ever played on a weak offensive team.

            > This is fun, splitting hairs!
            > If your center kicks out 3 nice passes to guards, who only hit one
            of
            > the 3 shots, the center only gets one assist.
            > The guard can make 3 nice passes inside, 2 of which may be
            converted,
            > so he gets 2 assists.
            > So an equally valid argument is that assists from guards
            > are 'easier', and assists from centers are 'undercounted'.
            > I say they are equal.
            >
            > Perhaps more to the issue, evaluate which players make those
            > practical passes which may or may not get them an assist, versus
            > those who will not give up the ball unless it gets them an assist.

            The goal is to identify when a good pass is made. Generally a better
            pass is one made to a better shooter. That's all I try to capture. I
            capture it in formulas with teammate FG%. For years, I didn't worry
            about it and it really didn't matter much. Now I've got more
            sophisticated calculation devices. I've actually found that this
            adjustment makes the most difference when evaluating different levels
            of basketball (high school, college, women's).

            Dean Oliver
            Journal of Basketball Studies
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