May 08, 2006
High Variance Home Runs
Sabernomics looks at the causes of the home run boom of the last decade plus and makes a good case that it's the distribution of talent among pitchers due to expansion that's the likely cause. I love this post, because it confirms something I wrote after the 1993 season. In The STATS Baseball Scoreboard 1994, page 90 there is an article titled What Does Expansion Affect More: Pitching or Hitting? Here's a scan from the book. The scan is Copyright 2006 STATS LLC, reprinted with permission.
Posted by David Pinto at
07:15 PM
|
Offense
|
TrackBack (0)
This is an interesting theory, but the numbers don't seem to work. Adding two teams to 24 existing teams just can't have this much effect. Even if we assume that the new pitchers in 1993-1994 were uniformly terrible -- let's say they allowed 6.0 R/G, compared to an average of 4.2 in 1991-92 among the existing pitchers -- that would only have raised scoring to about 4.3 R/G. In fact, R/G increased to 4.8 -- five times the increase that dilution might account for. (Similarly, dilution can only account for about 1/7 of the HR increase, with generous assumptions). And this ignores the fact that hitting was diluted as well.
Dilution of the pitching pool may play a small role here (though I'm skeptical, especially since the 1998 expansion had no effect on scoring), but mathematically it just can't be a major factor.
This is an interesting theory, but the numbers don't seem to work. Adding two teams to 24 existing teams just can't have this much effect. Even if we assume that the new pitchers in 1993-1994 were uniformly terrible -- let's say they allowed 6.0 R/G, compared to an average of 4.2 in 1991-92 among the existing pitchers -- that would only have raised scoring to about 4.3 R/G. In fact, R/G increased to 4.8 -- five times the increase that dilution might account for. (Similarly, dilution can only account for about 1/7 of the HR increase, with generous assumptions). And this ignores the fact that hitting was diluted as well.
Dilution of the pitching pool may play a small role here (though I'm skeptical, especially since the 1998 expansion had no effect on scoring), but mathematically it just can't be a major factor.
Guy is precisely right.
And further, the suggestion that the 70% increase in hit batsmen results from expansion makes no sense at all. Here are the year-by-year pitching HBP leaders (http://www.baseball-reference.com/leaders/HBP_p_leagues.shtml). The figures are higher over time, but the leaders remain, as often as not, very good or Hall of Fame quality pitchers. The increase in HBP more likely results from batters' willingness to be hit a 90+ fastball due to equipment changes.
