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  • #31
    Indeed...some things are illogical and yet ingrained.

    Like current park factors, for example.

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    • #32
      Originally posted by Tango Tiger View Post
      Tom to God: Please tell Sean Forman that most people are not aware that you cannot do anything with ERA+ unless they first take its recipricol. ERA+, unlike every other stat, puts the league figure in the numerator instead of the denominator. So, in order to do any kind of adding of ERA+, first do 1/ERA+, then weight it, then take the recipricol of that. Thank you God.

      God to Sean: Make it so.
      I think you are missing my point.

      Let's say that a player pitches 2 seasons, and in one he has a 2.00 ERA in a 4.00 environment and the next year a 3.00 in a 3.00.

      His two year's ERA+ scores are 200 and 100.

      His ERA+ average of rates will be 7/5 or 140.

      Now another player goes 3.00 in a 6.00 environment one year and then 3.00 in a 3.00 environment. His two years ERA+ scores are 200 and 100

      but his ERA+ average of rates will be 150!

      It is WRONG to give these two players different composite ERA+ scores simply because player 2 was at half the league average in a year that HAPPENED to be at a higher run environment than the year that player 1 put up half the league rate.

      It gives preference to seasons with a higher run environment.

      The math IS wrong. Back up man. (what I mean is take a step back and see that these are two DIFFERENT "problems"). The ratio issue is not a math problem. The averaging of run environments is. 2/3 + 3/4 is not 5/7
      Last edited by brett; 02-06-2008, 03:50 PM.

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      • #33
        Originally posted by Tango Tiger View Post
        The 100 infection is fine. I just don't get the 150 preference over 67 for ERA, but that it's OK to have an OPS+ for your star pitcher at 67!
        I think the >100 as opposed to the <100 is a semantic interpretation of the "+" as opposed to the "ERA."

        Both positions have their logical merits.

        "Relative ERA" would make me more inclined to think in terms of numbers below 100.

        The + in the title of the stat initially calibrates me on "higher number, better" paradigm.
        THE REVOLUTION WILL NOT COME WITH A SCORECARD

        In the avy: AZ - Doe or Die

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        • #34
          The whole + paradigm is wrong for pitchers and fielders though. What you need to do is use pythagorean logic and turn defensive numbers into offensive equivalences like THT does with its' PRC stat.

          Once you state how much a pitcher is worth in terms of equal value from a hitter, you can work with stuff a lot easier.

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          • #35
            Originally posted by digglahhh View Post
            I think the >100 as opposed to the <100 is a semantic interpretation of the "+" as opposed to the "ERA."

            Both positions have their logical merits.

            "Relative ERA" would make me more inclined to think in terms of numbers below 100.

            The + in the title of the stat initially calibrates me on "higher number, better" paradigm.
            And this is also true. There has been a strong implication that a player with a 200 OPS+ is producing twice as much as a player with a 100 OPS+ which IS approximately true within the limits of OPS+ itself. As a result, the ERA+ also implies a linear value relationship which is not true even within the limits of ERA.

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            • #36
              Originally posted by brett View Post
              I think you are missing my point.

              Let's say that a player pitches 2 seasons, and in one he has a 2.00 ERA in a 4.00 environment and the next year a 3.00 in a 3.00.

              His two year's ERA+ scores are 200 and 100.

              His ERA+ average of rates will be 7/5 or 140.

              Now another player goes 3.00 in a 6.00 environment one year and then 3.00 in a 3.00 environment. His two years ERA+ scores are 200 and 100

              but his ERA+ average of rates will be 150!

              It is WRONG to give these two players different composite ERA+ scores simply because player 2 was at half the league average in a year that HAPPENED to be at a higher run environment than the year that player 1 put up half the league rate.

              It gives preference to seasons with a higher run environment.

              The math IS wrong. Back up man. (what I mean is take a step back and see that these are two DIFFERENT "problems"). The ratio issue is not a math problem. The averaging of run environments is. 2/3 + 3/4 is not 5/7
              The first case, his career ERA is 2.5 in a league of 3.5, ERA+ of 140.

              The second case, his career ERA is 3.0 in a league of 4.5, ERA+ of 150.

              The math is not wrong, though. However, I see your point...
              Author of THE BOOK -- Playing The Percentages In Baseball

              Comment


              • #37
                How about a pitcher at Coors? Let's say he pitches 90 innings, with an ERA of 3.0, while the rest of the league does 6.0, and away from Coors in 90 IP his ERA is 2.5 and the rest of the league is 4.0.

                So, his Coors ERA+ is 200 (or 50% my way) ad his away ERA+ is 160 (or 62.5% my way).

                A straight average of 50% and 62.5% would give you 56.25%, which is an ERA+ of 177.8.

                However, his seasonal ERA is 2.75 in a league of 5.00, meaning an ERA+ of 181.8 (or 55.0% my way).

                So, it's not even a question of the year-to-year change in run environment causing "problems", but simply the change in run environment for each start causing problems.

                Good job on Brett for bringing the issue up. You really need to do this at the game level. If you don't have that, then at some split level. If you don't have that, then at the seasonal level. If you don't have that, then the way b-r.com does it.

                Whatever you do though, you cannot base it on ERA+, but rather its recipricol.
                Author of THE BOOK -- Playing The Percentages In Baseball

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                • #38
                  You don't have that environment problem if you turn everything into offense equivalence. Pythag logic applies.

                  In fact, I might be inclined to rate pitchers the same way I rate teams...PythagenMatt.

                  Comment


                  • #39
                    How does putting things in "offensive equivalents" solve Brett's issue when it exists for hitters as well?

                    Suppose Player A creates 5 runs in a league with an average of 4, then 6 in a league with an average of 6. His relative figures are 1.25 and 1, which by Brett's weighting comes to 1.125. (5+6)/(6+4) = 1.1.

                    Player B creates 6.25 against an average of 5, then 6 against an average of 6. His relative figures are 1.25 and 1, which again come to 1.125 by Brett's weighting. (6.25+6)/(5+6) = 1.114.

                    Comment


                    • #40
                      If you put both offense and defense into pythagorean context, the problem is gone, Patriot.

                      On the pitching side, offensive equivalence begins with pythag...which is why I said it solved the problem.

                      Comment


                      • #41
                        I think what Matt is saying, is equivalent to Brett's position of weighting the index by playing time.

                        That is, if you turn everything into a win%, you get the same scale for every game (or split or season). So, you can play at Coors one day, where the run scale is 6 runs per team, and play at the Astrodome another day where the run scale is 3 runs per team. But now, instead of adding each player's RC27 in the numerator and each league's run context in the denominator, you first convert each game into a win% (or in Brett's case, into an index).

                        The point of Matt is that each game should be its own universe, and it shouldn't disproportionately impact the ERA+ or RC+ or whathaveyou as you add more games.

                        So, index each game. Determine the weight of that index for the game.
                        Repeat for all games.

                        The index would either be a Pythag-based win%, or just the standard ERA+ type of scales.

                        (With the understanding, always, that ERA+ and other types of +constructors should be player divided by league.)
                        Author of THE BOOK -- Playing The Percentages In Baseball

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                        • #42
                          I should also add that this will barely make any difference anyway. We are really arguing on the technicalities here.

                          But, the b-r ERA+ problem is a math problem, and is wrong.
                          Author of THE BOOK -- Playing The Percentages In Baseball

                          Comment


                          • #43
                            As I understand Matt's "offensive equivalencies", he looks at a pitching staff that allows 4 runs in a 5 run context, and says that should produce a .610 W% (or whatever it is exactly; I just used a Pyth exp on 2). In a 5 run context, an offense that scored 6.25 runs would also produce a .610 W%, so 6.25 is the "offense equivalent" performance of the pitching staff.

                            The W%s will work, I agree. The equivalent runs scored figures will be subject to the same issues when you aggregate them as the 1/ERA+ numbers are.

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                            • #44
                              That's why I don't advocate aggregating in terms of RS though...I recommend aggregate W% figures weighted by PT and then converting to a run figure.

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                              • #45
                                Right, Matt is suggesting that once you've gone what you have to at the game level, then runs disappear, and all you have left are win% and "games" (with games being determined by whatever method is appropriate).

                                Similarly, we can do the same thing with RC+ (runs created indexed to 100, with runs created being whatever your favorite method is) and "games". Again, once you have that, runs disappears, and you are left with your index.
                                Author of THE BOOK -- Playing The Percentages In Baseball

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