Looking at FIP and SIERA

Starting pitchers for the Milwaukee Brewers ranked 22rd in FIP and 17th in SIERA last season. In order to understand these numbers, however, we need to go over what FIP and SIERA mean. After all, one of our goals is to inform the public on advanced statistics, so we shouldn’t automatically assume you know what all these weird stats are.

We’ll start with Fielding Independent Pitching or FIP.

Most of you are probably at least somewhat familiar with FIP as it is extremely popular in the sabermetric community. FIP attempts to estimate a pitcher’s ERA in the future by measuring only what a pitcher can control; walks, hit batters, strikeouts and home runs. A pitcher has little control over balls in play, so FIP completely ignores that aspect. I like FIP more than SIERA, but that’s only because it’s more well known and I understand it better. For a much better and in-depth explanation of FIP, check out the FanGraphs library.

Skill-Interactive ERA or SIERA is another ERA estimator. SIERA places a higher emphasis on strikeouts, and while walks are bad, they’re not as bad as FIP suggests. SIERA also doesn’t ignore balls in play. SIERA says that pitchers who allow less contact will force weaker contact from hitters. In other words, ground balls are good. Additionally, pitchers who have higher fly ball rates allow fewer home runs per fly ball. Again, go to FanGraphs to learn more.

Now that we have some understanding of these statistics, let’s compare FIP and SIERA among Milwaukee’s starting pitchers.

FIP SIERA Difference
Yovani Gallardo 3.94 3.78 0.16
Kyle Lohse 3.95 4.04 -0.09
Wily Peralta 4.11 3.73 0.38
Matt Garza 3.54 4.02 -0.48
Marco Estrada 5.73 4.04 1.69
Mike Fiers 2.79 2.76 0.03
Jimmy Nelson 3.82 3.76 0.06

These seven starters combined for a 3.98 FIP, 3.73 SIERA and 3.72 ERA. In terms of ERA, they outperformed their FIP and were basically identical with SIERA. Individually, SIERA and FIP were not far from each other, with the exceptions of Peralta, Garza and Estrada. However, SIERA was more favorable to every pitcher but Lohse and Garza. But why?

Well, Lohse and Garza owned a 17.3 K% and a 18.5 K%, respectively, but still held opposing hitters to a lower batting average on balls in play than other pitchers with similar strikeout rates. Remember, SIERA assumes that pitchers who strikeout more batters also give up weaker contact. Neither Lohse or Garza were big strikeout pitchers in 2014, but still managed to limit their BABIPs.

If you’re wondering why Estrada’s FIP is so high, I have two words for you : home runs. Luckily, Estrada’s back where he belongs in the bullpen, so we won’t have to worry about him killing the curve again next year.  I wrote about Estrada’s struggles here.

Milwaukee’s starting rotation was dependable in 2014, and we should see some sort of improvement from their young guys next year. It’ll be interesting to see whether or not Fiers is the real deal and if he can sustain his fantastic numbers.

Once again, if you want a primer on statistics like FIP and SIERA, head on over to FanGraphs.com. That site is fantastic and they’re the best at what they do.

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