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RE: [APBR_analysis] Re: Dampier (was Article from _The Economist_)

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  • Michael Tamada
    ... From: igor eduardo küpfer [mailto:edkupfer@rogers.com] Sent: Tuesday, April 06, 2004 9:17 AM From: Mike G To:
    Message 1 of 21 , Apr 6, 2004
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      -----Original Message-----
      From: igor eduardo küpfer [mailto:edkupfer@...]
      Sent: Tuesday, April 06, 2004 9:17 AM

      From: "Mike G" <msg_53@...>
      To: <APBR_analysis@yahoogroups.com>

      <snip>
      >> Maybe the data that shows "most players" have peaked before age 28
      >> are biased by the effect that marginal players are peaking at age
      >> 23 -- and out of the league by age 27.
      >>
      >> Meanwhile, average players may peak at age 25, done by 29. (Numbers
      >> off the top of my head)
      >>
      >
      >I looked at peak Manley Credit performances for 54 All-NBA players. I
      >plotted the aging curve here:
      >http://members.rogers.com/edkupfer/images/peakperformance.htm
      >The decline after age 30 is precipitous. Only 14 of 48 (29%) 31-year-olds
      >maintained their 30-year-old performances.
      >
      >
      >ed


      Nice, it could be part of a "basketballgraphs.com" website, a counterpart
      to "baseballgraphs.com". However it looks like your aging curve is based
      on all the plotted points? I think it'd be better to instead plot 54
      separate aging curves, and take the average of them ... wait no that would
      lead to the same result that you already got. I guess what I mean is this:
      if we're looking at a 29 year old Dampier or whoever, and trying to predict
      what his age 30, 31, etc. stats will look like, then we don't want to look
      at the overall average for 30-year olds (or 30-year old all-NBAers, or
      whatever group). Instead we'd want to look at what the typical *change
      in performance* is for a 30-year old, compared to what he did as a 29-year
      old. And then correcting for the things that MikeG mentioned: big players may
      "age more slowly"; star players may also. Also, players who rely on quickness
      or jumping ability may have more problems when they hit 30. Players who rely
      on outside shooting are an interesting conundrum: their bread-and-butter
      techniques can keep them playing into their late 30s or even 40s (Dale Ellis,
      Steve Kerr, etc.). But on the other hand, an inside-oriented player who
      starts getting old has the potential to change his game and increase the
      dimensions of his offense, specifically by developing an outside shot -- and
      can thus prolong his career or slow down his decline. Jordan and Erving
      certainly did this; dunking less and shooting outside more as they got older.
      I think Karl Malone did too, at least I don't remember him taking as many
      outside shots in his younger days.


      --MKT
    • Mike G
      ... wrote: .. ... to predict ... to look ... NBAers, or ... *change ... 29-year ... It so happens I ve been doing something like this. I also corrected for
      Message 2 of 21 , Apr 7, 2004
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        --- In APBR_analysis@yahoogroups.com, "Michael Tamada" <tamada@o...>
        wrote:
        ..
        > if we're looking at a 29 year old Dampier or whoever, and trying
        to predict
        > what his age 30, 31, etc. stats will look like, then we don't want
        to look
        > at the overall average for 30-year olds (or 30-year old all-
        NBAers, or
        > whatever group). Instead we'd want to look at what the typical
        *change
        > in performance* is for a 30-year old, compared to what he did as a
        29-year
        > old.

        It so happens I've been doing something like this.

        I also corrected for what might be considered a "bias" in a manley-
        type production figure: the NBA has overall been
        losing "productivity", on a per-game basis. Thus, all 30-year-olds
        have been around long enough to see a significant decrease in
        production, among all players.

        My figures show a per-game/per-team high around 144 in the mid-'80s,
        which has since dropped to about 125. Not sure of the manley
        formula Ed used, but I'm applying one equally to teams and
        individuals; using a formula like the one BobC layed out.

        Briefly, I see an average change based on age that looks like this:

        %inc is average increase (decrease if negative) of the age group
        that went on to play the next year, in "manley credits".

        SS# is sample size (player-seasons since 1978)

        age %inc SS#
        18 .897 3
        19 .332 12
        20 .353 30
        21 .130 94
        22 .224 360
        23 .113 729
        24 .044 771
        25 -.011 734
        26 -.020 700
        27 -.065 625
        28 -.071 562
        29 -.094 519
        30 -.129 453
        31 -.171 374
        32 -.125 274
        33 -.181 203
        34 -.183 142
        35 -.178 91
        36 -.246 62
        37 -.319 36
        38 -.236 20
        39 -.026 8
        40 -.246 3
        41 -.271 2
        42 -.604 1

        For 519 players age 29 who went on to play in their 30th year, an
        average loss of 9.4% has occurred.

        Earlier studies have shown an erosion of minutes, on average, from
        year to year in a player's career. No doubt, this is a part
        contributor in the total production a player loses. I'll be back
        with per-minute losses due to aging.
      • igor eduardo küpfer
        ... From: Mike G To: Sent: Wednesday, April 07, 2004 8:44 AM Subject: [APBR_analysis] Re: Dampier (was
        Message 3 of 21 , Apr 7, 2004
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          ----- Original Message -----
          From: "Mike G" <msg_53@...>
          To: <APBR_analysis@yahoogroups.com>
          Sent: Wednesday, April 07, 2004 8:44 AM
          Subject: [APBR_analysis] Re: Dampier (was Article from _The Economist_)


          <snip>
          >
          > I also corrected for what might be considered a "bias" in a manley-
          > type production figure: the NBA has overall been
          > losing "productivity", on a per-game basis. Thus, all 30-year-olds
          > have been around long enough to see a significant decrease in
          > production, among all players.
          >
          > My figures show a per-game/per-team high around 144 in the mid-'80s,
          > which has since dropped to about 125. Not sure of the manley
          > formula Ed used, but I'm applying one equally to teams and
          > individuals; using a formula like the one BobC layed out.
          >

          I used a no-coefficient MC formula. I don't think it will make much
          difference.

          > Briefly, I see an average change based on age that looks like this:
          >
          > %inc is average increase (decrease if negative) of the age group
          > that went on to play the next year, in "manley credits".
          >

          [...]
          >
          > For 519 players age 29 who went on to play in their 30th year, an
          > average loss of 9.4% has occurred.
          >
          Breaking down into statistical categories, here's what I have for
          30-year-olds:

          Poss -.066
          2% .005
          eFG% .007
          FT% .002
          OR% -.014
          DR% -.023
          AST -.011
          BLK -.065
          TO -.018

          Possessions are down 6.6%, accounting for much of the Manley Credits
          decrease. (I'm using medians for the numbers above.) Shooting percentages,
          however, are largely unchanged. The other stats have a lot of noise. My web
          page has all this in graphical form:

          http://members.rogers.com/edkupfer/images/effects_of_aging.htm


          --

          ed
        • Gabe Farkas
          i m curious, among the elite players, who at age 34 experienced a 300% increase in both offensive and defensive rebounding? ...
          Message 4 of 21 , Apr 7, 2004
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            i'm curious, among the elite players, who at age 34
            experienced a 300% increase in both offensive and
            defensive rebounding?


            --- igor_eduardo_k�pfer <edkupfer@...> wrote:
            > ----- Original Message -----
            > From: "Michael Tamada" <tamada@...>
            > To: <APBR_analysis@yahoogroups.com>
            > Sent: Wednesday, April 07, 2004 12:02 AM
            > Subject: RE: [APBR_analysis] Re: Dampier (was
            > Article from _The Economist_)
            >
            >
            > >Interesting differences in the graphs; the first
            > one suggested a peak at
            > age 26
            > >then a strange final peak at age 30 followed by
            > steep declines. The second
            > >and third graphs, which I believe to be the better
            > ones, suggest a peak at
            > ages
            > >26 and 27 (age 27 averaging 100% of the age 26
            > performance) followed by 3
            > almost
            > >flat years and then a substantial decline after age
            > 30.
            > >
            > >BobC's numbers seems to be based more on seasons in
            > the league rather than
            > age, but
            > >seem to point to peaks at age 24-25 and declines
            > starting around 29-30, so
            > a year
            > >or two earlier. But he was looking at a broader
            > set of players than the
            > All-NBAers,
            > >and it wouldn't surprise me if MikeG is right that
            > the star players have
            > later peaks
            > >or at least delayed precipitous declines, relative
            > to the kinds of players
            > who are
            > >washed up at age 31.
            >
            > I've uploaded a few more graphs, focusing on
            > specific stats:
            >
            >
            http://members.rogers.com/edkupfer/images/effects_of_aging.htm
            >
            > They show that some things, like FT% and defensive
            > rebounding rates, are
            > largely unaffected by aging, while other stats, like
            > turnovers and
            > possessions, are largely determined by a players
            > age.
            >
            > I hope my graphs are clear. I don't know too much
            > about making them, and
            > used this opportunity to practise a bit. The details
            > of each graph show the
            > interquartile range, between which half of all
            > observations can be found.
            >
            >
            > ed
            >
            >


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          • igor eduardo küpfer
            ... From: Gabe Farkas To: Sent: Wednesday, April 07, 2004 7:17 PM Subject: Re: [APBR_analysis] Re:
            Message 5 of 21 , Apr 7, 2004
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              ----- Original Message -----
              From: "Gabe Farkas" <gabefark@...>
              To: <APBR_analysis@yahoogroups.com>
              Sent: Wednesday, April 07, 2004 7:17 PM
              Subject: Re: [APBR_analysis] Re: Dampier (was Article from _The Economist_)


              > i'm curious, among the elite players, who at age 34
              > experienced a 300% increase in both offensive and
              > defensive rebounding?

              Er, that is an error. That was Marques Johnson, who did that after missing
              two seasons. The increase was over his 31-year-old performance.

              ed
            • Michael Tamada
              ... From: Mike G [mailto:msg_53@hotmail.com] Sent: Wednesday, April 07, 2004 5:44 AM [...] ... [...] ... So players peak at age 25 by your calculations, very
              Message 6 of 21 , Apr 8, 2004
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                -----Original Message-----
                From: Mike G [mailto:msg_53@...]
                Sent: Wednesday, April 07, 2004 5:44 AM

                [...]

                >age %inc SS#
                [...]
                >24 .044 771
                >25 -.011 734

                So players peak at age 25 by your calculations, very similar
                to BobC's figure. Younger than the figure that Ed had, but
                of course he was looking at all-pro players.


                --MKT
              • John Hollinger
                And other players such as Terry Cummings and Ron Harper ... just becoming ... Cummings? I don t think Terry Cummings will stop shooting until he dies or his
                Message 7 of 21 , Apr 10, 2004
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                  And other players such as Terry Cummings and Ron Harper
                  > seem to extend their careers by stopping from shooting period, and
                  just becoming
                  > defensive role players.
                  >

                  Cummings? I don't think Terry Cummings will stop shooting until he
                  dies or his arm falls off.
                • Michael Tamada
                  ... From: John Hollinger [mailto:alleyoop2@yahoo.com] Sent: Saturday, April 10, 2004 5:58 PM ... Oops, right you are. Still he did _reduce_ his shooting later
                  Message 8 of 21 , Apr 12, 2004
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                    -----Original Message-----
                    From: John Hollinger [mailto:alleyoop2@...]
                    Sent: Saturday, April 10, 2004 5:58 PM

                    > And other players such as Terry Cummings and Ron Harper
                    >> seem to extend their careers by stopping from shooting period, and
                    >just becoming
                    >> defensive role players.
                    >>
                    >
                    >Cummings? I don't think Terry Cummings will stop shooting until he
                    >dies or his arm falls off.

                    Oops, right you are. Still he did _reduce_ his shooting later in his
                    career, after ... was it a leg injury, or the heart problem, that
                    caused him to miss most of the 1993 season? Anyway, prior to that
                    he jacked up FGas at a Cummings-esque 25+ per 48 minutes; after that
                    he was under 18 per 48. Which is not exactly shy shooting, but I do
                    remember noticing the difference in his style when he played with the
                    Sonics; he was basically a role-playing backup center instead of a
                    shot-happy PF.


                    --MKT
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