Amphetamine Testing's Effect on Day Game Stats

This season for the first time MLB is testing players for amphetamines. I've heard a couple sources suggest that this might have a particularly sharp affect on day games when players like to "bean up" to get going earlier. I decided to check out how the day game stats relative to the night game stats are looking this year compared to other years.

I started wondering about this today when trying to decide whether to pitch Chris Capuano on Sunday afternoon at Wrigley. Cappy is one of those pitchers who really struggles during the day. The first pitcher I discovered who had this problem was Curt Schilling, back when he pitched for the Phillies. He was getting shelacked by the Cubs one weekday afternoon, and they posted his day/night splits to show it was nothing new. Curt's actually gotten a lot better at pitching during the day: his day ERA is 3.67 compared to 3.27 at night. But his career Wrigley stats still reflect his old struggles: 4.79 ERA, 2 wins in 9 starts.

Capuano's numbers led me to decide not to pitch him Sunday:
Career Day: 10-11, 4.69ERA, 1.42WHIP
Career Night: 19-15, 3.89ERA, 1.29WHIP
2005 Day: 7-5, 4.68ERA, 1.43WHIP
2005 Night: 11-7, 3.50ERA, 1.35WHIP

It's something a savvy fantasy pitching manager should keep an eye on. Some pitchers just prefer the night. But is it less important this year, because of the amphetamine testing?

Let's check out the numbers. I should note that amphetamines were/are supposedly used the most for day games following night games. I don't have quite enough time on my hands to track those stats down so you'll have to settle for just day v. night, a comparison that would still be affected if the theory is true.

2006 Day MLB Avg: .2642
2006 Night MLB Avg: .2664

So 2006 hitters prefer the night, just like Chris and Curt. Is that a change from last year? Let's see...

2005 Day MLB Avg: .2635
2005 Night MLB Avg: .2649

Well, that doesn't tell us too much, does it? You'll note I had to carry the averages to four digits to even see the difference between the Day averages. But the night average is actually .0015 higher this year.

Of course, a better comparison would be April 2005 day/night splits to this year's splits so far. (I wonder if cool nights are more detrimental to pitchers than to hitters?) But, again, I can't find stats that specific.

I guess our conclusion is the amphetamine ban doesn't seem to be having much of an affect so far. Perhaps later in the season, averages will start to dip. The Sports Sauna will keep an eye on it. Until then, I will recommend buying stock in any coffee bar with locations in and around MLB stadiums.