Charlie Mikolajczak writes in with an interesting question:
A couple of buddies and myself were hoisting a few yesterday when we started talking about the Vazquez trade. My one buddy absolutely loves JV and things he's a lock for a ridiculous season since he's on a team that's gonna give him run support now (the #'s his threw out were PlayStation like and obviously liquor-influenced, but you get the point). Anyway, he seemed to think that he'll be able to have a great season despite the shaky Yanks D is because he's a strikeout pitcher. While I think he's gonna have a good season in NY, I pointed out that his K's are most likely to go down by about 30 this season because he no longer gets the benefit of whiffing the pitcher 3 times a game. I tried to do a quick comparison on recent pitchers K's after switching leagues but it's a pretty short list for a good comparison. Just curious as to your thoughts on it...
Well, I did a little research...
That's a good question. Unfortunately, it's not as straightforward as one would anticipate. There are actually two pposing "forces".
Since the institution of the dreaded DH, the AL has had a significantly lower strikeout percentage. Ks per 9 IP have been between 5-10% lower in the AL over the last decade. The highest percent difference was in 1978, 13.5% lower, and the lowest was .78% in 1987. On average, pitchers strike out about twice as often as the baseball population taken as a whole (about 30% of all plate appearances as opposed to 15% over the last decade). All this translates into about .3 or .4 strikeouts fewer per every 9 IP in the AL. For Vazquez's 230.2 innings last year, that only translates into 10 fewer strikeouts.
However, it appears that pitchers in the AL have been allowed to go deeper into games because they did not to be pinch-hit for. I say appears because all I can go on is the stats for pitchers who have started exclusively since baseball doesn't split out its data historically by starters and relievers. Using that group, it appears that pitchers in the AL pitch between 1-3% longer. Given the splits in ESPN for 2003, starters in the AL did last 1% longer in the AL (5.87 IP/GS vs. 5.90, or .55%). So if Vazquez pitches 1% longer next year, he would have an extra 2-3 strikeouts. If it's closer to 3%, then it's 6-9 strikeouts.
So overall, the first "force" seems to be the stronger one, but either way, there does not appear to make too much of a difference. Especially, since his K/9 IP shot up from 6.99 to 9.40 last year. I'd be more concerned about his propensity to give up the long ball.
Remember that when Jeff Weaver was traded mid-2002 to the Yankees, his strikeouts-per-nine innings went up by 1 (5.55 to 6.58). It's not all about strikeouts. By the way, his strikeouts-per-nine innings was a career low 5.25 in 2003.