May 29, 2017
The Ervin Santana Disagreement
As you know, different pitching estimators tend to agree on which pitchers are good and which ones are not. The interesting cases are when they disagree—strongly. In those situations, the proper response is not to decide which one is “correct” (to the extent there is such a thing), but rather to look at why they disagree.
On a related note, people have recently asked for us to do more explaining of how Deserved Run Average (DRA) works. Often, it’s easiest to do that with an example.
Today, our example is Twins right-hander Ervin Santana. Santana has a 1.80 ERA, a 1.80 RA9, a 4.00 FIP, and a cFIP of 102, but a DRA of 2.74. He is striking out 6.4 batters per nine innings, walking 3.5 batters per nine innings, and giving up just under one single home run per nine innings.
ERA and RA9 suggest an extraordinary pitcher; FIP and cFIP see an average pitcher, and DRA sees him somewhere in between, as a very good, but not-as-good-as-his-RA9 pitcher. Why the difference in opinion?
FIP and cFIP, as you know, look only at home runs, strikeouts, hit batsmen, and walks. Santana gives up a below-average number of home runs, generates fewer strikeouts than average, and gives up a tad more walks than average. Home runs count for more than the other aspects, so he comes out as an average-ish pitcher overall.
DRA sees a more interesting profile. Santana has a left-on-base percentage of 91 percent and a batting average on balls in play of .136. If you look at Santana’s player card, you’ll see that he has played in hitter-friendly stadiums (pitcher park factor, or PPF, of 107), faced roughly average opponents (oppTAv of .258), and most importantly of all, has held batters to a True Average of .173. Since the league TAv is .260, this is an incredible amount of damage control on contact.
DRA applies linear weights after adjusting each event, so strand rate isn’t a factor; ignoring it is certainly consistent with Santana’s DRA being almost a full run higher per nine innings than his charged RA9. But the interesting things here are the BABIP and the True Average allowed. FIP expresses no opinion on balls in play at all. This often is just as well. But the disadvantage is that when a pitcher does exert meaningful control over balls in play, FIP will not pick it up outside of home run prevention.
Although luck has plenty to do with it, Santana’s results on balls in play are simply too low to completely deprive him of credit. Twins pitchers overall have a BABIP of .263 and a TAv allowed of .253. Although the BABIP and True Average figures need to be discounted to some extent, it is most likely that some of it is justifiably credited to Santana. That is what DRA is doing here: shrinking the credit, but still giving credit where each model sees it as being due.
The DRA runs leaderboard is your friend here. In addition to each player’s DRA, we tabulate each player’s total NIP runs (not-in-play events like strikeouts, HBP, and walks), Hit runs (value of hits allowed), and Out runs (essentially, an adjusted BABIP) above average. The simplest thing to do is to look at the sign next to each value: if the value is negative, the pitcher is performing better than average in that category (runs saved, if you will). If the value is positive, the pitcher is performing worse than average in that category (extra runs allowed).
As you can see, Santana is below average in NIP runs (consistent with a pitcher who generates fewer strikeouts and greater walks on average), but the best in baseball at controlling Hit runs (restricting damage on contact); his Out runs are also above average.
None of this means that Santana will necessarily keep his RA9 (or DRA) that low all year. It does mean that a pitcher’s ability to restrict damage done on balls in play, and to keep some balls from being hits at all, is worthy of at least partial recognition. DRA’s ability to do that is one reason to keep an eye on its assessments, particularly when they diverge from other estimators.