Wednesday, June 27, 2012

The Chad Billingsley versus Chris Capuano Deathmatch

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The big debate has been about how much better Chris Capuano has been versus Billingsley, the worst pitcher to ever play the game. At least, this is the way it usually goes with casual Dodgers fans. And it is not as if they do not have an argument. Look at the list of Dodgers starters by ERA:

Billingsley: 4.15
Capuano: 2.60
Eovaldi: 4.04
Harang: 3.81
Kershaw: 2.74
Lilly: 3.14

I guess that this is the source of the argument that I've heard that Capuano has been pitching better than Kershaw. It seems absurd, but the ERA numbers are right there. Billingsley looks to be the worst pitcher on the staff. But let's go one step further. Let's look at ERA- which corrects for park and league.

Billingsley: 108
Capuano: 68
Eovaldi: 105
Harang: 99
Kershaw: 72
Lilly: 82

Aha! Even by more advanced statistics Capuano is leading the pack. Billingsley is still the worst. Lilly is surprisingly good. However, ERA is subject to some dangerous lurking variables, namely BABIP, LOB%, and the whim of the scorekeeper (what counts as an earned run and what does not). So what if we look at xFIP-? This is an advanced statistic that only looks at strikeouts, walks, and flyball rates. So any issues from defense, scorekeeper, etc., are not factored in.

Billingsley: 100
Capuano: 99
Eovaldi: 110
Harang: 116
Kershaw: 85
Lilly: 120

Now we're starting to see something change. Kershaw now becomes the best pitcher on the team, while Billingsley and Capuano are about the same, and Harang and Lilly are just awful. This agrees more with our expectations.

So now I will add in my final statistic. This looks at SIERA, which is easily the best ERA predictor that is publicly available. From that, comparing to a SIERA of 5 as being the worst possible, I can look at how many runs each pitcher has prevented, and since not all of these pitchers have pitched the same amount, can look at SIERA runs prevented per game played. This way, I can account for how well they pitched, and how deep into the game they went. Here are those numbers. SIERA/GS stands for SIERA per game started while also considering how deep a player went into the game (any inning not pitched in a game is given a value of 5 SIERA). SIRP is Skill Independent Runs Prevented which compares to a SIERA of 5. It is a counting statistic and not a rate statistic, so keep that in mind when comparing players.

Billingsley: 4.16, 12.55
Capuano: 4.07, 13.97
Eovaldi: 4.65, 2.11
Harang: 4.60, 6.00
Kershaw: 3.64, 21.74
Lilly: 4.75, 2.04

Some interesting facts come out of this analysis. First of all, Kershaw has easily been the best pitcher in the group this year. He's almost equal to the production of Billingsley and Capuano combined. Lilly and Eovaldi have basically been the same pitcher. Harang is bad. Capuano has been better than Billingsley, but they are not miles apart. They're fairly similar pitchers.

In the end, everything is just as we expected. Kershaw is great, Billinglsey and Capuano are about the same and good, Harang is not so good, and Eovaldi has been matching Lilly's production (which apparently isn't much). I guess, then, that I could see getting another starting pitcher, but the offense just seems so much worse right now. More importantly for right now, though, can we stop the Billingsley hate and Capuano praise? If you want more out of Billingsley that's fine, but don't act as if Capuano is suddenly the second coming of Koufax.

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