Nate Silver is a writer for Baseball Prospectus, and he didn't call me dumb specifically, but he did say it's dumb to use ERA as a predictive statistic.
To reiterate, the key difference between these two sets of projections boils down to the predictive value of ERA; if Zito’s ERAs were an accurate reflection of his ability (as our “dumb” projection assumes), then this contract would have been perfectly reasonable. 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.
So what does PECOTA predict for Barry Zito?
PECOTA is not terribly optimistic about Zito, whom it regards as a just a hair better than a league average starter.
Wow. And what is he worth?
It thinks that Zito’s next seven seasons are worth $43 million in present value.
An average annual value of just over six million dollars a year.
We can't take this as gospel, of course. PECOTA is far from perfect. But it's probably better than a rough-hewn guess, which is certainly what I (or most people) would be able to manage on their own.
So who's buying this? Do we trust PECOTA and the peripherals? Is Barry Zito really going to be a league-average starter for the next seven years? Somehow, it's hard to swallow. Mostly because if he is, I'll have to apologize to Keith Law in 2013.
One more thing: are there instances of pitchers who consistently outperform their peripherals -- that is, guys who, year after year, allow fewer runs than you might predict?
Labels: barry zito, pecota
