I've been thinking about putting together a series about how the Royals can catch up to the other teams in the AL Central and make the playoffs in 2012, so the first thing I wanted to do was see how close the Royals are. In doing so, I discovered something that really surprised me:
The best run differential in the AL Central is Detroit's -4 mark. The Royals are third in the division at -49, a mere 45 runs behind the Tigers.
Naturally, I wanted to get a sense for how the Royals could close that gap, and the first place I looked was the starting rotation. I figured I'd start by looking at the luck-neutral metrics for our current starters, and then I'd take out the crappiest starter and plug in someone good like CJ Wilson or Edwin Jackson and say, "Look! This is how close we could be if we just made a big FA signing!"
Well, it turns out I never made it that far because I made a second discovery that really surprised me:
80% of the gap in run differential between the Royals and the Tigers disappears when you neutralize luck in the Royals starting rotation.
For my luck-neutral pitching metric, I chose SIERA. For those who aren't familiar with SIERA, it gives you a sense of what a pitcher's ERA should be if they had neutral luck with BABIP and HR/FB. In this sense, it's very similar to xFIP, but it gives pitchers who miss a lot of bats or induce a lot of groundballs or flyballs credit for being hard to square up, and slightly lowers their expected BABIP. It's actually slightly harder on most of the Royals starters than is xFIP.
Then I calculated how many more or fewer earned runs each pitcher would have given up were their ERA equal to their SIERA. Here's what I found:
In other words, if these Royals starters had had neutral luck this year, they would have given up about 39 fewer runs combined, pulling them almost even with the division-leading Tigers in run differential.
I ignored the starts from O'Sullivan, Mazzaro and Adcock, figuring that every team gets crappy spot starts from AAAA pitchers during the season. I decided to take those starts as built-in 'bad luck' that will be back next year, so I didn't neutralize it. But if you wanted to say that O'Sullivan, Mazzaro and Adcock's numbers should be luck-neutralized, you'd get another 6 or so runs back, which would make the Royals dead-even with the Tigers.
This method has some obvious short-comings. I didn't neutralize luck for any of the other teams in the division, I didn't look at luck in the Royals bullpen, I didn't regress anything to the mean, and half of the starters I listed won't even be back next year.
Still, this one simple step of neutralizing luck in the starting rotation puts the Royals near the top of the AL Central in run differential without any significant moves or FA signings. I think that's a good starting point when considering the Royals chances to contend in 2012.