Sunday, April 26, 2009


Do yourself a favor and change the 'Year' value on this page at a few times. See if you see anything strange about some of the names that appear at the top of the list of the Twins most valuable pitchers.

They're relievers.

And often not even closers. For instance, last year Jose Mijares was more valuable than Glen Perkins, Nick Blackburn and Kevin Slowey. In 2007, Pat Neshek and Matt Guerrier were more valuable than any starting pitcher. In 2006, see where Juan Rincon is on the list. In 2005, check out Jesse Crain. In 2004, Rincon again. 2003 was LaTroy Hawkins and 2002 was JC Romero.

That list is sorted by a stat called WPA, which is Win Probability Added. It kills me not to go into the details too much, because the details are truly elegant, but you can find them here. You can think of it as a measure of how much each player helped along the probability of their team to win a game.

The beauty of WPA is that it is descriptive. It is NOT that it is predictive or evaluative. It isn't. For instance, using WPA, a slugger who hit three home runs in one game might not be as valuable as a utility player who got a couple of lucky singles in another. Because the home runs might have happened when a game was out of reach, and the lucky singles drove home the winning run in extra innings. You wouldn't claim that the slugger is worse than the utility player. You wouldn't claim he'll be worse than the utility player. But you would claim that in those games, he wasn't as valuable as the utility player. (And if you wouldn't, ask yourself, why not?)

So if reliever throw so few innings, why are they getting such high WPA scores? Why do they appear more valuable?

Because high-impact relievers can be used when games are on the line. They are, essentially, trump cards that managers can play. And looking around the Twins organization, there should be plenty of optimism of the hand that Ron Gardenhire might soon be dealt.

First and foremost, Jose Mijares looked awesome on Friday night. Giddy awesome. Twins-Geek-giggling-in-Maxwells awesome. Protecting a 3-1 lead in the eighth inning against top of the Indians lineup, he overpowered Grady Sizemore, Mark DeRosa and Victor Martinez.

We could also talk about the weekend that Luis Ayala had. Or Craig Breslow and Matt Guerrier's appearance. Or the promise of Juan Morillo. Or even the other-wordly numbers that Anthony Slama and Rob Delaney are putting up in New Britain.

But it's late, and they all say the same thing: the bullpen is a work in progress. But the key word is "progress".

More Stuff
We tried something new for the podcast, and I'm really happy how it turned out. We - gasp - actually got together and talked face-to-face. Seth and I were also joined by Kyle Eliason, who in addition to being a master sound engineer, is all about harshing on Rays. I hope you like it. And finally, if you really want to get ready for the upcoming series against the Rays, check out our Pitching Probables on


Nick N. said...

And this, ultimately, as the biggest problem I have with WPA. It's a fun little metric to look at, but how can we put much stock into a statistic which claims that Bobby Korecky and Jose Mijares -- who combined to throw a whopping 28 innings last year -- were both more valuable than Kevin Slowey -- who threw 160 innings with an above average ERA?

John said...

Thanks Nick! YOu just gave me a topic for tomorrow!