A few weeks ago I wrote about the "hangover effect" that some say causes the Rockies' hitters to perform poorly on the road. I didn't find any evidence of the effect and went on to postulate that perhaps the Rockies have been the unwitting victims of "altitude bias". Once again, I didn't find much evidence to support that speculation.
Finally, I read an article in the Rockies official magazine that referred to a "pitching hangover" that Greg Maddux and others say affects them after pitching at altitude.
Although the article mentioned that the hangover was relatively short in duration, I wondered if pitching at Coors Field had a persistant effect that could be measured. To test this I looked at the 2003 and 2004 seasons and measured the performance of visiting starting pitchers in their Coors Field starts compared with the first start after. The reasoning being that if Coors Field produced a hangover, perhaps the next start for the pitcher which show it through decreased performance. Here's what I found.
IP H TB K BB WHIP K/9 BB/9 H/IP
Start at Coors 874.3 1082 1837 588 356 1.64 6.05 3.66 1.24
Next Start 875.3 889 1412 652 310 1.37 6.70 3.19 1.02
Other Starts 18199.3 18175 29175 13471 5933 1.32 6.66 2.93 1.00
As you can see in the starts at Coors the performance was predictably worse than would be expected as evidenced by increased walks and hits per inning pitched and decreased strikeouts. What's interesting is to compare the second two lines which show the pitcher's next start and then all their other starts excluding these two. Although both hits and walks per inning pitched are higher in the next start, the margin is so small that I doubt that shows any kind of real effect. In fact, in 2003 pitchers actually did better in the start after a Coors Field start than in others.
So I wouldn't put too much credence in the "pitcher's hangover" for starts anyway. Relievers might be a different story, however, since they pitch more frequently...