McGwire and Bradbury, the Sports Economist

For the third straight year, allegations of steroid use kept Mark McGwire from election into the Baseball Hall of Fame gathering only 23.7% of the vote in 2010.  This week, he acknowledged steroid use in a tearful apology.  As a preface to my remarks, I admit to liking McGwire.  He appeared more likable than many athletes.  In his rookie year, he hit 49 home runs, but forewent the opportunity to hit 50, sitting out two games to witness the birth of his first child.  When negotiating a contract, he signed with St. Louis Cardinals when other teams were offering more because he liked the cities and franchise's baseball tradition.  He gave a million a year to a charity helping abused children.  Joel Stein of Time provides a good biography in "Mark McGwire: Mark of Excellence."  It was written in 1998, before the steroid's scandal broke.  Is steroid use the only viable explanation for McGwire's performance?

J. C. Bradbury's book, "The Baseball Economist" is a must read for students who like baseball, economics and statistics.  He offers the hypothesis that baseball expansion is another explanation for the spike in home runs between 1998 and 2001 than steroids use.  Roger Maris hit 61 home runs in 1961 when the Los Angeles Angels and Washington Senators joined the American League.  His second highest home run total was 39.  Baseball expanded prior to the spike in 1993 and 1998.  The causal relationship is that as the league expands, talent becomes more dispersed.  On average, the best hitters face worse pitching, and vice versa.  Bradbury writes,

What does this say about the current ear of baseball history, especially given the intense public focus on steroids as the cause of the increased number of home runs?  Pitching talent is more dispersed than it has ever been, while hitting talent is still quite concentrated.  It means there are plenty of batters out there who are able to take advantage of bad pitchers.  A more dispersed pitching talent pool gives the best hitters greater opportunities against weaker talent, which ought to lead them to perform extreme feats...

Also, if low-quality pitchers are hitting more batters, shouldn't better pitchers benefit from facing more bad hitters as hitting talent has become less compressed since the 1980s?  In fact, they do, as pitchers increased their strikeout rates over the same span....

Bradbury concludes,

The fact that talent dilution may be part of the cause for the great performances of players does not mean that steroids have not influenced the game.  However, it's certainly incorrect to say that steroids, or other performance-enhancing drugs, are the only explanation.