The necessary caveat for a review of Jon Gray’s first 40 major league innings—about 20 at home and 20 away—is that the sample is small. That might seem self-evident; but his few innings have not prevented a little too much hand wringing from skeptics and a little too much laudation from the optimists. The sample is too small to really justify either position. It’s not, however, too small to let lie unanalyzed. So let’s dive in.
The first thing to note about Gray’s first 40 innings is not to take ERA at face value. The reason is because ERA is good at describing final results, but it doesn’t pay attention to how it got to those results. This is a lesson that many observers have yet to internalize. Gray’s 5.53 ERA overall is unmistakably and undeniably bad. Think of it as a car crash, which might be appropriate. A car crash is also unmistakably and undeniably bad. There’s really no such thing as a "good car crash." The fact quality of the car crash, like the 5.53 ERA, is not in dispute. Similarly, Gray’s sparkly 2.70 road ERA and his sullied 8.27 home ERA are not in question. But not all cars crash in the same way. There are extraneous circumstances that must be factored in. Who, if anyone, was at fault? Things like the weather or the experience of the drivers might also contribute.
The primary extraneous circumstance to explain Gray’s ERA is his batting average on balls in play (BABIP), which measures the opponent’s batting average excluding strikeouts, walks, and home runs (outcomes that don’t factor in defense). BABIP is a fair indicator of how lucky or unlucky a pitcher has been based on how far it deviates from the league’s BABIP. Gray’s .384 BABIP against in his first shortened season is 85 points higher than the league’s .299. This suggests that more of the balls hit into play have landed for hits than was to be expected.
In fact, it’s not even common for a starter to have such a high BABIP. Among starters who have pitched at least 40 innings since 1961, Gray is one of 16 to have a BABIP against of .384 or higher. Exactly one of those pitchers ended up with a respectable ERA (24 year-old John Lamb’s 4.60, which oddly enough took place this season). Gray’s BABIP woes have been accentuated at home, where it stood at .429, which is way above the composite .343 BABIP at Coors Field this year. A good part of Coors Fields’ hitter friendliness is a BABIP above league average, but it’s not .400 friendly.
The thing about BABIP, however, is that league average is often portrayed as some sort of cosmic rule. It’s not. Let’s assume for a moment that I could throw a baseball from a pitching mound over home plate, but I don’t have any other pitching tools. My BABIP against would not be .299. It would be much, much, much higher. It also wouldn’t mean the high BABIP against was due to luck. Instead, it would be due to a word that rhymes with luck. Suck is the word; it would be because I suck. So a .384 BABIP can be a real indicator of a pitcher’s ability. For example, one of the 16 starters to post such a high BABIP in at least 40 innings was a 40 year-old Kevin Brown, whose skills had decayed.
Thankfully, there are other bits of information we can look at to try and determine whether or not we should question ability. Namely, allowing line drives usually leads to a higher BABIP against. Year-to-year, line drive BABIP tends to be between .650 and .700, so allowing a lot of line drives will lead to a higher BABIP against without it being due to luck. Gray has been below average in this respect. In all of baseball this year, 20.9 percent of batted balls have been line drives, whereas 24 percent of Gray’s have been line drives. He’s been a tick under league average in terms of groundball rate and fly ball rate.
It’s difficult to draw conclusions from Gray’s batted ball profile because his splits suggest that his fortunes should be reversed. It’s at home, not on the road, where Gray has limited line drives and induced more groundballs. Not incidentally, groundballs generally have a higher BABIP than other balls in play, which explains his .429 home BABIP, but groundballs also have the advantage of rarely being extra base hits. Additionally, Gray limited fly balls at Coors Field, which do have a tendency to travel over the outfield wall one out of every ten times. In short, mapping Gray’s home/road ERA onto his batted ball profile doesn’t make a lot of sense.
Not all outcomes result in a ball in play, which is where walks and strikeouts come in. Walks and strikeouts are sometimes referred to as "peripheral" statistics, but they are anything but. Pitchers who walk a lot of batters and strike few out are rarely successful. Earlier this season, I wrote that those areas were by far the most worrying parts of Eddie Butler’s game, and they remain so. But Gray has been doing just fine in these areas. He’s struck out 8.85 batters per nine innings, which is excellent. Gerrit Cole’s 2015 K/9, for instance, is 8.91. Gray has walked 3.1 batters per nine. Walks per nine figures that approach four are worrisome. Those in the low threes are not great, but also not bad. And if we mush the K/9 with the BB/9 to get a strikeout to walk ratio, Gray’s comes out to 2.86. That figure isn’t far off from Gray’s 2.84—the other Gray, Sonny.
While Jon Gray’s batted ball profile was better at home than on the road, his walks and strikeouts were better on the road. But that assertion comes with a qualification. On the road, Gray struck out a Kershaw-esque 11.25 batters per nine innings. Conversely, he struck out a less impressive 6.53 per nine at home. But on the road, Gray also walked more batters per nine, 3.6, than he did at home, 2.6. The result was actually a better K/BB at home than on the road, 3.13 to 2.50. For all the talk of Gray’s splits, this is one area where his overall numbers hold the story. Gray’s MLB 8.85 K/9, 3.1 BB/9, and 2.86 K/BB practically mirror his minor league figures: 8.9, 2.9, and 3.04.
These factors show that ERA shouldn’t be taken at face value. Luckily, we have ERA estimators that try to account for these underlying factors. Recall the car crash analogy. A car crash, in itself, is evidence that a car crash took place. But any given crash does not predict other crashes. Similarly, ERA is not a good predictor of future performance. Other statistics are though.
One is FIP, which stands for Fielding Independent Pitching. As opposed to BABIP against, it accounts only for outcomes without a ball in play (strikeouts, walks, and home runs) so as to eliminate ball in play luck and defense as variable outside of the pitcher’s control. It’s scaled to look like ERA. Jon Gray’s FIP is 3.64. Because 3.64 would be a desirable ERA, a 3.64 FIP is a good sign for Jon Gray. On the road, Gray’s FIP is 2.65, which is very close to his road ERA of 2.70. At home, his FIP is 4.67, which is not bad at all for Coors Field. Another ERA estimator is xFIP, which is FIP adjusted for league average home run to fly ball ratio, which is about nine percent in 2015. Because Gray 14.5 percent of Gray’s fly balls at home have been home runs, his xFIP is even better than his FIP at 4.22. On the road, however, Gray’s 5.0 percent home run to fly ball ratio leads to a 3.48 xFIP on the road. The takeaway is that in a collection of numbers that range from acceptable to great, Gray’s ability likely lies in the middle.
There’s a better ERA estimator than FIP and xFIP that accounts for much more than just a slice of outcomes. Baseball Prospectus’s cFIP, which stands for contextual FIP, accounts for almost everything measurable: the weather, handedness of opponent, park, umpire, catcher, and base runners. cFIP has been shown to be better at predicting future performance than any other metric. Based on a 40 inning sample, cFIP thinks Gray has been about seven percent better than league average. Other starters with the same cFIP in 2015: Sonny Gray, Taijuan Walker, Mike Fiers, and J.A. Happ. Each of these pitchers has much more innings, but over Gray’s first 40, cFIP sees a major league pitcher.
The last time I was in Colorado covering a Rockies game, Bryan Kilpatrick and I were chatting about statistics with Cory Sullivan in the dugout. He said something to the effect of "players don’t care about FIP." In one sense, he’s wrong. If players care about walks, strikeouts, and home runs, they care about FIP. They just don’t call it FIP. The same can be said about cFIP and each of its components.
In another sense, though, he’s right. I have no delusions that I can make Jon Gray feel better about his 5.53 ERA by informing him of his cFIP. Jon Gray isn’t my audience for this piece though. The purpose of it is to save the Rockies watcher's hands from violent offseason wringing. It’s still possible that the inability to make mental adjustments can derail him, but he’s made mental, as well as mechanical, adjustments in the past, so I trust he’ll do so again.
Advanced statistics might help prevent a crisis of confidence for some players, but I don't think Gray is one of them. Because of that, we should keep in mind the anxiety that Nick Groke recently reported when we watch Gray pitch next season, especially at home. It's up to the Rockies coaches to get his mind on something else, because all other on the field factors suggest he's going to be just fine.