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Re: [APBR_analysis]

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  • HoopStudies
    ... hypothesis: Player ... tested ... would be ... games. ... suspect ... probabilities, ... solve ... I tried it, too. I forgot about it until you
    Message 1 of 36 , May 1, 2002
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      --- In APBR_analysis@y..., "Michael K. Tamada" <tamada@o...> wrote:
      > won-loss records to calculate a player's probability of not being a
      > replacement level player (I forget what won-loss percent he used as
      > replacement level). I.e. he literally created a null
      hypothesis: "Player
      > X is a replacement level player, with a won-loss % of .abc" and
      tested
      > those 5-2, 8-8, or whatever records against that null hypothesis.
      > Players who were close to .500, but who played a lot of games,
      would be
      > very unlikely to be replacement level players. Ditto players whose
      > records were far above .500, and who had a reasonable number of
      games.
      >
      > A clever idea, a nice try, but James eventually dropped it, I
      suspect
      > because he found the same thing that I did: the resulting
      probabilities,
      > if used to rank players, resulted in strange-looking, not very good
      > rankings. Fiddling around with different replacement levels didn't
      solve
      > the problem.
      >

      I tried it, too. I forgot about it until you mentioned it. I like
      your other idea, though, a little better.

      >
      > A better solution would be something like this: figure out what the
      > replacement level is (something like .415 or something like that
      seems to
      > be popular in baseball, it is likely to be a different number in
      > basketball). And simply calculate wins above replacement. A 5-2
      record,
      > compared to the 2.9-4.1 record that a replacement level player
      would have,
      > is 2.1 wins above replacement. An 8-8 record, compared to the 6.6-
      9.4
      > that a replacement player would have, is 2.4 wins above replacement.
      >
      > So in your example question, my off-the-cuff estimate was
      incorrect, the
      > 8-8 player contributed more to the team.

      OK. Defining replacement value is an interesting challenge. James
      used 0.350. I always felt like basketball's number was lower, maybe
      about 0.200-0.250. If baseball's worst teams win about 35% of their
      games and that corresponds to replacement level, then shouldn't
      basketball's worst teams set replacement level? Basically an average
      player on the worst team is probably a bum. Think of all the guys on
      those rebuilding Chicago teams as pretty much replacement level (that
      includes, interestingly, Brent Barry).

      Conceptually, I'd think this replacement level number goes down with
      increasing league size. More players means more bad players, in
      general. Does that make sense?

      I really do like this idea, though, MikeT. If we say that 0.25 is
      replacement level, then Duncan's 17.1-0.7 record is 12.7 games above
      replacement level. McGrady was 8.7 games above replacement level.
      Ewing was 0.3 games above replacement level. Troy Hudson was 0.1
      games above (though I know a lot of guys like him more than that, he
      has generally been considered pretty close to replacement level).
      And by this measure, sure enough, I do find that Erick Dampier has
      edged out Michael Olowokandi for farthest below replacement level (-
      2.0 to -1.5). Actually, I didn't do the calcs for all players, but I
      did a few others and even Jason Spazz Williams didn't quite match
      these guys.

      >
      > So in your example question, my off-the-cuff estimate was
      incorrect, the
      > 8-8 player contributed more to the team.

      No, you were actually originally right. 8 - 6.6 = 1.4, not 2.4 as
      you wrote down. The breakeven point at which these 2 guys are
      equivalently above the replacement level is 0.330.

      DeanO
    • Michael Tamada
      Yeah, these are things to keep in mind as we try to zero in on the replacement level. Some so-called replacement level players are clearly better than others.
      Message 36 of 36 , Mar 24, 2004
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        Yeah, these are things to keep in mind as we try to zero
        in on the replacement level. Some so-called replacement
        level players are clearly better than others. Are they
        thus truly "freely available"? There's only one Rod
        Strickland; once he's signed, it's not possible for any
        other team to go out and sign him. On the other hand,
        he was in a sense available to any team that wanted him.

        I suspect we'll want to look at a bunch of players
        identified as replacement level and find their average value,
        to even out the occasional Strickland who brings up the
        average and the occasional Oakley or whoever who brings down
        the average.

        In other words, something more akin to KevinP's look at the
        average performance of free agents, instead of the 290th
        man approach. Although it turns out that they yielded
        very similar values.


        --MKT

        -----Original Message-----
        From: John Hollinger [mailto:alleyoop2@...]
        Sent: Monday, March 22, 2004 8:20 AM
        To: APBR_analysis@yahoogroups.com
        Subject: [APBR_analysis] Re: - wins/Tendex replacement


        I think at this time of year there's also multiple levels of "freely
        available" -- Level 1 is the guys who get waived in March (Dion
        Glover, Rod Strickland, etc.) so they can sign with a playoff
        contender. Level 2 is the guys the bad teams sign to replace them
        (Britton Johnsen, Josh Davis, etc.).... and Level 5,831 is Charles
        Oakley.



        --- In APBR_analysis@yahoogroups.com, "Michael Tamada" <tamada@o...>
        wrote:
        > -----Original Message-----
        > From: Kevin Pelton [mailto:kpelton08@h...]
        > Sent: Wednesday, March 17, 2004 11:45 AM
        >
        > >> > I'm not sure it will be easy to identify a replacement level.
        > >>
        > >> Wouldn't be easy, but I'd try various techniques: WAG (wild a**
        > >> guessing: what number seems reasonable?); looking at actual
        > >> transactions of players cut and added, especially those on 10-day
        > >> contracts; actual statistics of actual 12th men, etc. These
        > >> different techqniques would undoubtedly lead to different
        > >> definitions of what the replacement level is, but now at
        > >> least the range has been narrowed down.
        > >
        > >MikeT, I know you've mentioned this kind of study a number of
        times,
        > >and since I probably make more use of replacement level than
        anyone
        > >else here (Dan being the possible exception), I've wanted to do it
        > >for a long time and finally got around to it:
        > >
        > >http://www.hoopsworld.com/article_7557.shtml
        >
        >
        > That's really good stuff, exactly the sort of empirical study that
        was
        > needed. And I think we've got a good estimate of replacement
        level,
        > at least as measured by your efficiency statistic.
        >
        > The point about in-season vs truly "freely available" free agents
        is a
        > good one, and your stats show the importance of the distinction.
        You
        > seem to be saying, and I agree, that the higher level, out-of-
        season,
        > freely available free agent replacement level is the better one to
        use.
        > At least for making long run, multiple-season, comparisons of
        players.
        > Teams in the short run may end up with less-than-replacement-level
        > players due to contract restrictions, salary caps, or what not, but
        > those conditions will not or at least need not persist in the long
        run.
        >
        > I think your .425 or .430 estimate of the replacement level is
        probably
        > a good one, maybe it won't turn out to be 100% accurate but I'll
        bet it's
        > reasonably close to whatever the true figure is. Because you've
        used
        > multiple techniques to arrive at the same estimate: the 10th player
        > technique, and the free agents' stats technique.
        >
        > There is a subtle problem however with the 10th player technique.
        Intuitively,
        > one would think that the 12th player would be a better measure of
        the replacement
        > level player. But the stats of these 12th players might actually
        be poor
        > measures; they might be BELOW replacement value, and are only on
        the roster
        > due to guaranteed contracts or what not. Or they might be an 18-
        year old kid
        > being stashed on the roster but not expected to contribute yet. Or
        they might
        > just have turned out to have a bad year, with horrendous stats that
        plummet
        > them to 12th.
        >
        > So those are good reasons why the 12th men's stats are perhaps not
        a good
        > measure, they're likely to give us a figure that's below
        replacement level.
        > So taking the 10th man's stats, or more precisely the stats of the
        290th
        > guy in the league, might lead to better estimates.
        >
        > The subtle problem with all this is that your technique stacked the
        deck
        > against the 12th men from the beginning, because you order the
        players
        > by efficiency. So the 12th men are guaranteed to have the very
        lowest
        > efficiencies on your rosters, and thus have stats that are likely to
        > be below replacement level.
        >
        > And thus to come up with a figure that is a better estimate, you
        have to
        > "move up" the roster to the 10th position.
        >
        > A theoretically better technique (but one that is perhaps
        impossible to
        > actually execute) would be to look at the stats of players who we
        identify
        > as the 12th man *a priori*, i.e. before looking at their stats.
        Some of
        > these 12th men will be the Brian Cardinal types, with some decent
        stats.
        > Some of them will be the Ansu Sesay types, basic deadwood there to
        fill
        > the roster, literal replacement level players. Averaged together,
        their
        > efficiency will be higher than the average efficiency of the 12th
        man
        > calculated by looking at their actual stats and ordering them ("a
        posteriori"
        > stats rather than "a priori"). Indeed, if done correctly, I'd
        expect these
        > 12th men to have stats slightly above the replacement level, simply
        because
        > they were the 12th guys and not the 13th guys, the ones who truly
        will be
        > the replacements.
        >
        > The trouble with my a priori idea of course is how do we know,
        before
        > looking at the stats, who the 12th man is? For some teams, it's
        fairly
        > easy to identify, but for others, not. Probably we'd have to pick
        a couple
        > of players from each team, and estimate the stats of the 11th-12th
        men
        > collectively.
        >
        > There's another reason why the .425/.430 might be just a little
        high. It's
        > possible that the off-season pickups might not be as freely
        available as
        > we might think -- though undrafted, there might be a few teams
        willing to
        > snatch up these players, for their low cost, low risk, and
        potential
        > contributions. I.e. there may be some semi-decent free agents out
        there,
        > whose stats bring up the average, but who weren't really freely
        available
        > because other teams went after them and signed them. They were a
        bit better
        > than the truly freely available replacement players.
        >
        > However, you've got a great quote from Brian Cardinal which
        suggests that
        > this is not the case.
        >
        > Bottom line: I think this is a good estimate which likely is
        getting us into
        > the neighborhood of the replacement level. My guess is that if it
        turns out
        > not to be the correct value, it's because it's a shade high.
        >
        >
        > --MKT





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