Friday, May 23, 2008

Slamming the Door: What's It Worth?

You can also find a version of this article in the June issue of GameDay, sold outside of the Metrodome before Twins games.

I’m old. 41 likely may not sound very old to some of you, but my back, right knee and left ankle would argue otherwise, and they generally win most debates when they get cranky enough. But even when they remain fairly silent, it’s hard to argue otherwise when you’re older than one of baseball’s most often cited statistics. You see, I’m older than The Save.

The Save was defined in 1970, and like most things that came out of the 70s, it’s a little goofy. Some baseball purists would go further than that, considering it the single most evil thing to come out of that decade. That’s no small claim, given that the decade also produced disco and polyester. Oh, and Starland Vocal Band’s Afternoon Delight. That’s where the purists’ argument falls apart – they forget about Afternoon Delight. But I digress.

The Save is incredibly unpopular with the purists because they believe that it fundamentally changed how bullpens started being used. And they’re probably right.

Baseball historians have gone back and tallied the “saves” that players had before 1970, but before that, it wasn’t a formally defined statistic. Once we started counting them and keeping track of them, ballplayers wanted to start getting them. And The Save isn’t something that only occurs naturally in baseball games. It is also created.

For instance, a starter needs to be pulled to get a save, since a pitcher can’t get both a win and The Save. (That’s part of the goofy definition of The Save). Also, nobody gets the Save if a different pitcher is brought into a game to get the last out (because a pitcher must pitch at least a half inning to get The Save). Or if a pitcher is leading by four runs in the eighth inning, but gives up a run, he can’t get The Save if he still finishes the game in the ninth. On the other hand, if the manager brings in a closer for the ninth, he can get The Save. You get the idea.

The change towards gathering The Save was more gradual than you might think. Throughout the 1970s the number of saves didn’t change too much from what it had been in the 1960s. But a corner was turned in the early 80s, and the result was dramatic. Consider this: prior to 1983 the American League never had a season with 500 saves. And since 1983? They’ve never had a complete season where they didn’t exceed 500 saves. It was like a switch was flipped.

And that switch has led to some big changes in the game both on and off the field. On the field, bullpen moves have become more formulaic. If the Twins are leading a game by three runs in the ninth, who is going to be on the mound? Does it matter if the opposing team’s 7-8-9 hitters are up? Does it matter if Pat Neshek struck out the side in the eighth? Does it matter if Nathan just came from the hospital following the birth of his daughter? No, it doesn’t. He’s the closer. He gets The Save.

But what if the Twins are up by four runs? Well, then all bets are off, aren’t they? And there is no particularly good reason for this. Historically, home baseball teams entering the 9th inning with a three run lead have won 98% of their games. And home baseball teams entering the 9th inning with a four run lead have won 98.8% of their games. So is Nathan brought into the game for that last .8%? Or is it because the goofy definition of The Save allows him to get one if there is a three run lead?

It’s also led to some big changes off the field. Saves have become a commodity, one that is worth tens of millions of dollars. The Twins, a team that has recently developed closers from spare parts, joined that movement this spring when they signed Nathan for four years and $47 million dollars. If he averages about 70 innings per year for the next four years, that’s over $167,000 per inning. That’s much more per inning than the Mets will likely pay for Johan Santana.

And that’s what drives some of the stats guys crazy about The Save. They view wins and losses as naturally correlating with how many runs a team creates and prevents. And a closer can only prevent so many runs when he only pitches 5% innings of the 1400-1500 innings that represent a baseball season. It’s a terrible allocation of resources to spend that much money on a fraction of those innings.

But are all innings created equally? Doesn’t it make sense to have your best pitcher in those innings where they can complete a win? And shouldn’t that be worth something? Is there a way to measure that? And can I really justify a paragraph that consists of nothing more than five questions?

The answers are: No, Yes, Yes, Yes and Yes, because it's my blog, dammit. And we're all irresponsible renegades. Ask Buzz Bissinger.

The method for measuring that is called Win Probability Added, or WPA for short. WPA is how much a player improves the probability of their team winning a game based on historical results. It’s best explained using an example.

Say the Twins enter the bottom of the ninth trailing by a run. Historically, MLB teams have only won roughly 19% of those games. If Joe Mauer leads off with a single, he improves the Twins chances of winning. Historically, teams have won 32% of those games, so Mauer earned 13 (32% - 19%) of WPA. If Justin Morneau follows with a home run, the chances of winning the game are now 100%, so Morneau gains 68 (100-32) WPA.

It works on the other side, too. The closer who blows the save is charged negatively for all the WPA. When he came into the game, his team had an 82% chance of winning, and when he left, they had a 0% chance. So he’s charged -82 points.

It’s an elegant little statistic that mirrors how we tend to think about games. There are games that “we were supposed to win” and games won “single-handedly.” WPA’s biggest weaknesses are that it doesn’t take into account defense and you really need computers to do the number crunching. Fortunately, the internet is filled with computers, and they’ve been crunching those WPA for the last several years. Any guess who leads the Twins in WPA over the last four years?

It’s Nathan. In fact, he’s led the Twins in WPA for three of the last four years. (In 2005, it was Santana.) And he’s leading again this year. (For more info on WPA, I highly recommend the site, which supplied the WPA used for this story.)

And so, maybe The Save is not as overvalued as we might think. I won’t go as far as saying that something positive came out of the 70s, but I will recognize that maybe this is an example of us being able to learn something from a relative youngster.

And I’m looking forward to the next debate of what a closer is really worth. It beats arguing with my right knee.