Opposition Adjusted Winning Percentage

            This is just kind of a stupid little thing; I was just messing around with the data, not expecting to find anything really interesting, and probably I found even less than I expected.   But my thought was, what if you "weighted" each win and loss for a starting pitcher by the quality of the opponent?   In other words, if a pitcher gets a win against a team which wins 100 games, we count that as 100 wins, whereas if he wins a game against a team which wins only 60 games, we count that as only 60 wins—and vice versa, if he loses a game to a bad opponent, a team which lost 100 games, then we count that as 100 losses, whereas if he loses a game to a good team, a team which lost only 60 games, then we count that as only 60 losses.   How would that change the winning percentages?

            The one interesting thing that turns up from this study is that the pitcher who gains the most in a single season and the pitcher who gains the most in a career turn out to be the same pitcher:  Alex Kellner.   Alex Kellner won 20 games as a rookie for the 1949 Philadelphia A’s, a fluke season, and then led the league in losses the next two seasons, going 8-20 and 11-14; not often you could lead the league in losses with 14, but he did.   He hung around for a long time after that, and pitched well for the 1958 Cincinnati Reds, going 7-3 with a 2.30 ERA for them in seven starts and eleven relief appearances. 

            Anyway, Kellner in 1950 was 8-20, but 8-19 as a starting pitcher.  However, in my data he is only 8-14, since I am missing some of his games from my log.   In the games I have he was 8-14 as a starter (.364), but if you weight the wins and losses for the quality of competition he improves to .452, an 88-point improvement.    (The missing data does not cause the improvement; those games are missing both from the "natural" and the "quality adjusted" winning percentage.   As far as we know, they don’t exist.)

            Anyway, when we figure the CAREER records, Alex Kellner again is the pitcher who improves the most.   Kellner had a career record of 92-108, a .460 winning percentage, although in my data it is .459 (84-99).   But when you adjust for the quality of competition that he faced, his winning percentage improves to .495, a 36-point improvement.  

            Trying to figure out logically whether this adjustment would help pitchers on bad teams and hurt pitchers on good teams, I couldn’t figure it out, but when you check the data, it obviously does; all of the pitchers who are helped the most in their career winning percentages pitched mostly for bad teams, while those who are hurt the most pitched mostly for good teams.  

            What you may notice is that these numbers are not that large.   The questions I was asking were things like "are there any pitchers who might be in the Hall of Fame if this had been factored in?" and "Are there are any Cy Young Awards that might have gone to a different pitcher if this had been factored in?"   But a 36-point pickup in winning percentage (a) is not huge, (b) is larger than anyone else had, and (c) the largest pickups are for guys who had 100-200 career decisions.   Hall of Fame candidates need to have 350-500 decisions.   The gains and losses in that range are not that large.    The largest gain for anyone who might be looked upon as a Hall of Fame candidate is 14 points, for Billy Pierce.  

            Billy Pierce, 1950s White Sox pitcher. . . . .he was a little guy, and a two-pitch pitcher.   He just threw a fastball and a slider.   Well, early in his career he threw a big curve, but the big curve led to a lot of walks, and he "added" a slider.   Mostly the slider replaced the curve, and (according to contemporary accounts) he mostly just lived off of those two pitchers, although he would later claim that he threw all three.  

            Anyway, Pierce was a tremendous pitcher for a good long time.   He had a .553 career winning percentage as a starter, .554 in my data, but if you adjust for the quality of competition, it was .568, a 14-point jump.    Baseball Reference confirms that he did do the bulk of his pitching against quality teams.   The two teams that he started against most often in his career, the two teams against which he had the most starts, decisions, and innings, were the Yankees and the Cleveland Indians, the two best teams in the American League in his era.   In his career he started 187 games against sub-.500 teams, going 102-56 against them, but started 245 times against .500+ teams, going 109-113. 

            You can compare that to, let’s say, Jim Bunning; Pierce’s career winning percentage was 17 points higher than Bunning’s against sub-.500 teams (.646 to .629), and 20 points higher against .500-or-better teams (.491 to .471), but, because Pierce pitched most often against good teams whereas Bunning had 258 starts against sub-.500 teams, 261 against .500-or-better teams, their career winning percentages are almost the same.   It’s relevant; I don’t know if it puts Pierce over the Hall of Fame line or not, but it counts a little bit.   Perhaps a more interesting one is that Pierce and Don Drysdale have almost the same career won-lost records, 211-169 for Pierce, 209-166 for Drysdale—and almost exactly the same splits against good teams and sub-.500 teams.   Pierce was 102-56 against sub-.500 teams; Drysdale was 100-55.   Pierce was 109-113 against .500 or better teams; Drysdale was 109-111.  

            Anyway, the one Cy Young Award which seems like it might have gone the other way, had the voters been aware of this, is also Billy Pierce.   In 1957 Billy Pierce and Warren Spahn both went 20-11 as starting pitchers.   Both pitched a few times in relief, 3 times for Pierce, 4 for Spahn; Pierce took a loss as a reliever, making him 20-12, while Spahn picked up a win, making him 21-11.   That small difference, in the world in which the Cy Young Award rested very heavily on won-lost records, may well have made Spahn the Cy Young Award winner.  Possibly not; Spahn won 15 out of 16 votes, Pierce got none.   Anyway, back to the thesis; Pierce was 20-11 as a starter, but adjusting for the quality of the competition, he goes up to .703, while Spahn, also 20-11, goes down to .622, giving Pierce an advantage of 81 points, or 2 ½ games.   If Pierce had gone 22-10, let’s say, and Spahn had been 19-12—a 2 ½ game difference—Pierce quite certainly would have won the award.  So I think you can argue that this fact, had it been known at the time, might have given Pierce the award.  

            As we look at things in the modern world, Pierce might have won it anyway.   Pierce had far more strikeouts (171 to 111) with fewer walks (71 to 78) and fewer home runs allowed (18 to 23), so Pierce wins all three of the true outcomes.   Spahn had a better ERA, but Spahn gave up 13 un-earned runs; Pierce gave up 5.   None of that is really relevant to the current discussion. 

            Other than that, don’t really see any Cy Young Awards that would be changed by this knowledge.   Some of you will wonder about Pete Vuckovich’s notorious award, 1982; Vuckovich was 18-6, a .750 percentage, but if you adjust for the quality of the wins and the losses, it goes up .770, while Dave Stieb, who should have won the award if it was going to go to a starting pitcher, goes down from .548 to .545.   Doesn’t change my opinion; Stieb was still a better pitcher than Vuckovich, but what I am saying is, the quality of the opposition was the not the meaningful variable.   If you look at historic seasons—Carlton in ’72, Blue in ’71, Koufax every year, etc.—it doesn’t really change anything; they all come out about the same.   Dwight Gooden in 1985 (24-4, .857) adjusts up to .862; Whitey Ford in 1961 (25-4) adjusts down to .859.   I mean, we all know that Whitey Ford in ’61 was not really THAT good, but this method does not adjust for things like Run Support and Park Effects and Defensive Support; those are other issues.  A 1.000 winning percentage in this method is always 1.000 after you make adjustments, no matter how badly you pitch, and .000 is always .000, no matter how well you pitch. 

            It takes a lot to move the "opposition adjusted" winning percentage very far from the "true" winning percentage.  Frank Lary, notorious Yankee Killer, went 7-1 against the Yankees in 1958, 5-1 against them in 1959—but his winning percentages adjust upward by only 12 points in 1958, 31 points in 1959.   This chart summarizes the career data for Lary:

            Lary in his career was 127-111 as a starter, 1-5 as a reliever; we’re not missing any data for him, except that my game logs don’t include relief appearances.  This is the career data for Sandy Koufax:

            This is Bob Gibson:

            And this is Roger Clemens:

            You can see that this adjustment really doesn’t make any difference most of the time.   Whatever is wrong with the won-lost record, this adjustment is not going to fix it.