‘Sabermetrics,’ baseball and steroids
Prognostications are that Mark McGwire will not be inducted into Baseball’s Hall of Fame this year again, because of admitted steroid use. Here is the URL to the article:
In 2005, McGwire ducked the direct question whether he had used steroids or performance-enhancing drugs (PEDs). Many statisticians think that steroids do not improve performance, because “most baseball skills depend primarily on reaction times and judgments, factors unaffected (or even degraded) by these drugs.” Those who study the numbers, “sabermetricians,” (coined from SABR – Society for American Baseball Research) “think the writers should set aside their biases and moral indignation and look at the facts: there’s simply no evidence steroids or other PEDs actually improve performance in baseball.”
One of the quotes in the article states, “While Bonds’ home run output rose significantly in the years after he supposedly started taking drugs, his profile is strikingly similar to Babe Ruth’s high performance level almost right until the [end] of his storied career, they say.” The actual data do not support this statement as you can see in Figure 1, which compares Barry Bonds offensive performance against three of the other great hitters of the game: Babe Ruth, Ted Williams and Ty Cobb. I used http://www.baseball-reference.com/ as the source for my statistics.
Figure 1: Offensive performance comparison
The OPS+ statistic is a normalized statistic that is adjusted for opponents’ defensive strengths and ball park friendliness to hitters. A value of 100 is average performance. The above statistic shows that Barry Bonds performance was below that of the compared hitters for the first 15 years of his career and then suddenly and dramatically his performance soared for the remaining years of his career surpassing all prior years, when the offensive performance of the other hitters was definitely declining. Admittedly, this is arm-chair forensics, but the data suggest that steroid use did improve Barry Bonds’ performance.
Currently, Roger Clemens has emphatically denied that he took steroids. His trainer, McNamee is reported in the Mitchell report as stating that he injected Clemens with steroids from 1998 to 2001. Clemens is scheduled to testify before Congress and there are allegations of defamation of character being “batted” around.
Figure 2 compares Roger Clemens ERA (earned runs allowed) performance against three other great pitchers of their time.
Figure 2: ERA comparison
The ERA+ statistic is a normalized earned-runs-allowed statistic which has been adjusted for opponents’ strengths and other factors. A value of 100 is average. Clemens’ first year of baseball is 1984 and the four year period of 1998 to 2001 corresponds to his 15th through 18th years of play. The data show that during this time, Clemens’ performance was average. However, these data are unusual because some of Roger Clemens’ best years came after he turned forty, an age when nearly all players have retired from baseball and several years after the alleged steroid use.
While I did not expect to arrive at a definitive answer concerning these two players, I found it intriguing to apply forensic thinking to the current allegations of cheating and doping that are being circulated.