‘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:

http://www.nationalpost.com/sports/story.html?id=221516

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

Comparison of hitters

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.

http://www.bloomberg.com/apps/news?pid=20601079&sid=a0z.L9DGg68A&refer=home

Figure 2 compares Roger Clemens ERA (earned runs allowed) performance against three other great pitchers of their time.

Figure 2: ERA comparison

Comparison of pitchers

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.

 

Dennis Maynes

Chief Scientist, Caveon Test Security

1 Comment

  • I like what you are doing here. The graph is clear. Interesting that Clemens has more years. Who knows, one effect of PEDs is simply adding years. But I am still not sure that what Clemens is doing is unprecedented.

    When Cy Young was 39, his ERA+ was 86. When he was 40, it was 129. So it went up 50%. When he was 41, it was 194. so it went up 50% again.

    When Clemens was 40, his ERA+ was 112. When he was 41, it was 146. So it went up 30%. When he was 42, it was 226. So it went up 55%.

    Those two events look very similar. Just one year difference in age. Cy improved even more over the two years than Clemens.

    Then there is Ted Lyons. Here are his ERA+’s from age 33 on

    32-97
    33-97
    34-157
    35-101
    36-112
    37-132
    38-171
    39-137
    40-111
    41-173

    He pithced 180 innings at age 41 in 1942. Even in 1942, most of the good hitters had still not joined the military (Williams and DiMaggio, for example were still there). Lyons had a career ERA+ of 118. So in his late 30s and early 40s, he was generally pitching well above his career average. My point is that late career improvements are not totally unheard of (although not common). I am not sure what Clemens has done in terms of an unusual age profile is much different than Lyons or Young

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