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Thursday, January 11, 2007
Quality of Pitching in NL and AL
John Walsh wrote a great piece about OF arms in the Hardball Times Annual. It’s one of those great “well-presented, intensely-researched, easy-to-grasp” articles that I like. You don’t have to get the math-mumbo-jumbo to understand what’s going on. John is one of my favorite sabermetricians, and for that reason, I hold him to a higher standard. In his article:
http://www.hardballtimes.com/main/article/americans-defeat-nationals-in-pitchers-duel/
He says:
Another thing to note is a key assumption: this method assumes that the average park in the NL does not favor hitters over the average AL park, and vice versa. Standard park factors compare parks within a league—we have very little information on how AL parks compare to NL parks, simply because of the low number of interleague games. My intuitive feeling is that the assumption is a reasonable one, but it should be kept in mind, nonetheless.
Again, this is a sticking point, and it really sticks out. And, I’m a stickler. What John showed with 62% of dual-leagued players having a higher OPS in the NL is caused by three things: pitchers, fielders, parks. Yet, because he attributes the parks to be equal, without any justification, he concludes it’s because of the pitchers and fielders. This may be the case, but this has not been demonstrated.
What bothers me is when he further justified it as “low number” of interleague games. There have been, I believe, over 2000 interleague games since 1997. That’s more than enough to ascertain the run-generating effect of a typical AL and NL park. You still have to be careful of course, with parks being added/removed, and altered. But, Yankee Stadium and Shea Stadium haven’t changed much, if at all. There’s no reason that we can’t use all interleague games since 1997.
As well, though a likely minor point, how are AL and NL relievers used? And what’s the gap between the starter and reliever in each league? As we know, there is a huge gap in a pitcher performing as a starter than the same pitcher as a reliever. This would need to be addressed.
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As an aside: the average AL fastball pitcher is 1 to 2 MPH faster than the average NL fastball pitcher. That is likely fairly good evidence that AL pitchers are better. Or of course, there is a “gun” bias in AL parks, and we need a “gun” park factor.