“Barry Zito is going to start sucking any day now. He’s in decline. He’s been lucky. He’s losing it.”
I’ve been hearing words to that effect from the numbercrunchers for about four years now. I didn’t believe it then, and I don’t really believe it now, either.
Rich Lederer described the issue well:
To Zito’s credit, his actual ERA has consistently defied his FIP and DIPS calculations, as well as his PECOTA projections. He is obviously doing something well that isn’t being captured in these systems.
Over at Baseball Prospectus, Nate Silver found that if you use Zito’s past ERA as a predictor of his future ERA, his new contract is actually worth the money. If you use his peripheral numbers, the Giants are paying double what he’s actually worth. Silver writes:
But while ERA is a very useful backward-looking metric — it’s helpful in settling Cy Young Award debates, for example — it’s not such a good forward-looking metric. A pitcher’s peripheral statistics predict ERA much better than past ERA itself.
I’d agree with that 99% of the time, but I can think of several reasons why Zito may be an exception to the rule. Consider:
