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What to make of Jon Gray’s start to the 2019 season

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This is a Jon Gray we haven’t seen before

One of the major highlights of the season so far is the possibility that the starting rotation, already widely assumed to be the team’s strength, could be even better than we thought. That is largely due to Jon Gray. In the course of a year Gray has gone from the presumed top starter in the Rockies rotation to third fiddle, with Kyle Freeland and German Márquez the numbers one and two. Now, it’s looking like Gray may realizing his promise — to at least create a three-headed monster at the top of the rotation.

But this is baseball, and we can’t focus exclusively on results at the expense of process. Last May, I looked at the season Gray was putting together after his first 11 starts. In terms of process, he was having the best season of his career. His strikeouts were up and his walks were down. But in terms of results, he was having the worst season of his career. Gray’s ERA was well over 5.00. He was, in the end, just having the weirdest season of his career. While that analysis took place after about one-third of his season, it stuck throughout the year.

This year is different. In fact, so far this year, it’s almost opposite.

His process stats, the ones that tend to be more indicate of future performance, are slightly down. On a percentage basis, Gray is striking out about the same number of hitters, but his walks are up. He’s walking 10.2% of the batters he’s faced, which is about two percentage points higher than his previous career high. That means that his strikeout to walk ratio is also the lowest in his career, at 2.31 strikeouts per walk.

The one constant between this year and last year is that he’s just as prone to giving up home runs. In 2018, his home run to fly ball ratio was 18.1%. It’s 18.2% so far this year. The long ball was one of the things that did Gray in in 2018, but that hasn’t been the case in 2019.

Gray, in fact, is humming along right now with a 2.78 ERA. Despite walking more batters and a steady, and pretty high, rate of allowing home runs, he’s now in the midst of the best worst season of his career, as opposed to 2018’s worst best season.

Here are two ways to make sense of it.

Stranding runners

Over his first five starts, Gray is stranding runners at a higher rate than ever in his career, 86.4%. In 2018 Gray only left 67.9% of runners on. Strand rate is one of those stats that can be used to measure how lucky or unlucky a pitcher has been. The league average strand rate is consistently around 72%, and stranding batters is generally accepted as something that is a little outside of the pitcher’s control. So a strand rate above 72% suggests a pitcher has been lucky, while if it’s below it indicates unluckiness. There are extraneous factors though. For instance, some pitchers are better out of the stretch (like Gray), and some pitchers reliably have different results in tight situations (like Gray). Because it’s something everyone experiences, we know that pitchers may act and think differently in different situations.

One way to think about the discrepancies of Gray’s strand rate between 2018 and 2019 is to say he was unlucky last year and has been lucky so far this year. That may have something to do with it, but I wouldn’t discount other factors that are harder to capture, such as maturation and approaching runners on with a different and more effective mindset.


Gray’s pitch usage hasn’t changed much, but he’s getting a lot more groundballs than he ever has. His 57.5% groundball rate is a full 10 percentage points higher than it was in 2018, and it’s 8.5 percentage points better than his career high. It appears to be due to his fastball. Gray throws his four-seamer about half the time, and so far in 2019 the pitch has a 64.8 groundball per ball in play rate (according to Brooks Baseball). It’s not clear why the pitch is all of the sudden generating more groundballs (at least, it’s not clear to me), but it may be because it has a little more sink than in the past. (I’m only basing that on the fact that Brooks has classified a handful of Gray’s fourseamers as sinkers.)

If this holds up though, Gray’s results should as well. More groundballs end up as hits than fly balls, but they also tend to be singles rather than extra base hits.

Is there a “real” Jon Gray?

Obviously, Rockies fans want the 2019 Gray to be more real. If he can continue generating so many groundballs, he could even survive his really high home run to fly ball ratio. But if he continues to walk batters at his current rate, he’s going to have to work through runners on base more frequently, and that will put pressure on him to keep up his possibly unsustainable strand rate.

The “realest” Gray has ever been was 2017, when he had a 3.73 strikeout to walk ratio, and his strand rate and home run to fly ball ratio were both about league average. That season, he had a 3.67 ERA and a 3.18 FIP. Rather than weirdness, that was just a really good season, albeit a short one. The problem with wanting to return to that moment, however, is that Gray’s a couple years older and a slightly different pitcher. At the very least, his velocity is holding up.

“Something’s got to give” feels like the right thing to say about Gray’s 2019, especially after just five starts. But in 2018 the course of Gray’s season was already evident through 11 starts. Nothing really gave. Gray starts Saturday against the Braves in Atlanta. And based on his work so far, we know what to look for: Walks, home runs, stranding runners, and groundballs.

Let’s see how this one small part of Gray’s season turns out.