WPA: A stat for everyone (except Francisco Cordero)

I understand a lot of the resistance from old-school baseball people and fans to advanced stats. I really do. Advanced stats can be confusing and, because of both their naming and the math that goes into them, intimidating. There’s also the problem that, dammit, I just want to talk baseball and not what somebody might theoretically do over the next so many years, especially considering this or that park factor.

Can’t we just talk about what happened last night?

Can’t we just talk about where our team is in the standings and how they got there?

If the above describes how you feel, I sympathize. I’m not in total agreement, but I do share your feelings to a certain degree. And I have good news — if you’re like me and seeking a middle ground, at least — there is an advanced stat just for you!

Win Probability Added (WPA) is quite possibly the perfect baseball stat. For an in-depth explanation of the stat, I recommend this Hardball Times piece, but here’s a quick rundown of how it works:

  • Each team begins each game with a 50% chance of winning.
  • Certain events (scoring a run, getting out of a jam, etc) can change that chance of winning.
  • If a player does something to raise or lower his team’s chance of winning by, say 10%, that player gets credited with .1 or -.1 WPA.
  • Clutch performance matters. A late home run helps your team’s chances better than one in the first, just as a closer striking out the side in the 9th is worth a lot more than a starter striking out the side in the first.

Those are the basics and that’s all you really need to know (if I left out something important, please leave a comment and I’ll update the list).

The best thing, as far as I’m concerned, about WPA is that it’s largely intuitive. Based on the team’s performance so far this season, you’d probably expect Kelly Johnson and Edwin Encarnacion to lead the offence in cumulative WPA. And they do. As far as pitchers go, you’d likely expect Brandon Morrow to lead the team. And he does.

Who’s the worst player on the team in terms of WPA? That Francisco Cordero currently holds that honour should be no surprise to anyone. Through roughly a third of the season, he’s sitting at a total of -1.1.

Do you remember how bad Jon Rauch was last year? Brutal, right? Well, he only managed to accumulate -0.5 WPA throughout the entire season. Francisco Cordero has been that bad.

Fangraphs chart following the swings in win probability of last night’s White Sox-Blue Jays game, with important events highlighted.

Last night, Cordero contributed a whopping -0.37 to his WPA. And that makes sense, right? The stat blames Cordero, who gave up a walk-off hit to Orlando Hudson, for 37% of the Jays’ loss.

On the other side of the coin, Hudson gets .357 for his walk-off hit and Alex Rios (ugh) gets .253 for his home run to tie the game in the 6th.

So, what do you think? Is WPA the perfect middle ground between old-school stats and sabermetrics?

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