Jon Gray Needs to Change
Jon Gray was drafted third in the 2013 MLB Draft by the Colorado Rockies. He was seen as the second best pitcher in the draft, next to Mark Appel. Neither one has lived up to their draft selection. Appel selected first overall has already retired having never reached the majors, whereas Gray has pitched in the majors in parts of the last five seasons, which is the good news. The bad news is that he hasn’t become the ace that the Rockies envisioned, though he has been mostly above average.
Gray has seemingly been on the edge of breaking out since his first full season in 2016. He posted a 3.6 fWAR in just 168 innings while striking out 9.91 batters per nine innings. The ERA was ugly looking at 4.61, but his FIP painted a prettier picture sitting at 3.60 for the year. He followed up with a great 2017, equaling his fWAR total but unfortunately limited to 110 ⅓ innings. The peripherals continued to look great with a 3.18 FIP and a HR/9 rate of .82, no easy task when pitching at Coors Field.
Since then? Gray has taken a major step back. He’s started giving up home runs at the rate you would expect from a Rockies pitcher and he started walking more batters overall while his strikeouts have held steady. Is there an obvious symptom or issue here?
For one, Gray is getting hit harder than he ever has, with his Hard Hit% sitting at 43.3% according to Baseball Savant or if FanGraphs is your preferred venue, it sits at 39.9%. Either way, it’s his career high and higher than the league average. The interesting part is that Gray’s ground ball % is at 50%, combined with his K% of 23.5%, we should be looking at a slightly better performance, shouldn’t we?
I really want to focus on Gray’s pitch mix because I think it can give us insight into his shortcomings right now. The main focus will be his fastball, which was his plus pitch in college. At an average velocity of 96 miles per hour, this should be one of his strongest pitches, but it isn’t. Looking at Pitch Value, which attaches run values to pitches, Gray’s fastball has consistently graded as a negative value where zero signifies an average pitch.
To further illustrate, let’s use some tables and charts to show how his fastball is hurting his performance.
The first graph shows Gray’s top three pitches by usage (nearly 95% of his pitches are either fourseam fastballs, sliders or curveballs) with their corresponding wOBA (which is on the same scale as batting average) by season. We can see that his fastball is far and away a pitch that batters feast on. At it’s best in 2016, batters still posted a wOBA greater than .350, which is what you would see from an above average hitter. The rest of the stats tell the same story.
Year after year, Gray throws this pitch a thousand times and hitters get on base at a clip of 40% of the time. Gray doesn’t strike any batters out many batters with this pitch either. Think about Gerrit Cole or Justin Verlander. They have similar fastballs in terms of speed/velocity (something we will come back to), and use it often. Yet, they generate more swinging strikes with their fastballs and batters are producing wOBA under .300 and wRC+ less than 100. One more picture to try and further illuminate the issue.
Gray has never completed a season with a SwStr% higher than 6.8%. With a fastball like his, we should be seeing more swinging strikes than that. What’s impressive to me is that Gray has generated ground balls nearly 50% of the time over his career, while he only allows about 23% flyballs. I looked into whether Gray is unlucky when it comes to defense, but the left side of his infield is comprised of Nolan Arenado and Trevor Story, two fantastic defenders. The Rockies outfield ranks in the bottom of the majors in terms of defensive metrics, which could be an issue. But, of the 23% fly balls he’s allowed almost 19% have gone for homeruns in Gray’s career, which could be a hazard of pitching at Coors Field. So, that would seem to be more problematic than his outfield’s defense.
Remember when I talked about Gray’s fastball velocity being comparable to Verlander and Cole? Well, in recent years we’ve learned that not all 96 mile per hour fastballs are created equal:
The above images demonstrate one of the main issues with Gray’s fastball. It ranks in the 10th percentile or lower in terms of spin rate. Gray is one of the only pitchers whose spin rate sits around 2060 RPM to also throw that pitch over a thousand times according to Baseball Savant. Unless he gets traded to the Astros and they can magically add RPM to his fastball, Gray cannot continue to use his fastball this much.
Gray ranks 9th of all qualified Major League starting pitchers when it comes to fastball usage. He also ranks 9th when it comes to usage of a slider. There is precedent for a pitcher throwing more breaking pitches than they do fastballs and I think Gray could benefit from a change in his pitch usage.
Generally speaking, pitchers who throw their fourseam fastball less than 50% of the time, they usually have another hard pitch, like a sinker or cutter, that they throw instead. Gray doesn’t seem to have a good sinker or at least one that he’s comfortable with. So we’d be looking to change his pitch mix from 50% fastball, 33% slider and 11% curveball to some mix of <50% fastball, >40% breaking balls.
There is precedent for this. Clayton Kershaw would have the most similar pitch mix, with a 39.8% usage of sliders and 16.9% use of curveballs and limiting his fourseam fastball to just 42.5% of the time. Yu Darvish is another example, throwing his slider 46.7% of the time and his fourseam 27.8% but Darvish also has another four to five pitches that he mixes in as well.
I think Gray would benefit from using his slider close to 40% of the time and his curveball at around 16% of the time, leaving around 40ish% fourseam fastballs plus any combo of sinkers and change-ups that he would want to throw (he throws both combined around 5% of the time).
Why am I so adamant? Well we’ve seen teams embrace the idea of pitchers throwing their best pitches more often. Remember how I showed the counting stats for Gray’s fastball? Let’s take a look at his curveball and slider counting stats.
The curveball is good in a small sample. It generates a swinging strike 13.6% of the time and batters have only produced a 45 wRC+ and a .230 wOBA for his career. The curveball has produced a strikeout against 38.5% of the batters Gray has faced. He doesn’t seem to have great control or command of the pitch, as generally it’s not thrown in the zone more than 39% of the time.
For his entire career, batters have produced a 48 wRC+ to go with a .235 wOBA against his slider. Gray essentially turns batters into a light hitting shortstop with both his breaking pitches. He clearly has command of the pitch as well, since batters only walk 4.5% of the time when he throws it in his career. Meanwhile he’s struck out 38.7% of batters, which is otherworldly. He seems comfortable with it, as he’s able to throw it in the zone more than 42% of the time during his career and he’s gotten swinging strikes 20.7% of the time.
Currently, just by playing percentages, hitters can be comfortable guessing that one out of two times, they’re going to see a fastball and that there’s around 55% of the time that same fastball is going to be in the strike zone. If we bring the usage of fastball and slider closer in terms of percentage, then hitters will have a harder time sitting dead red on fastballs, because there’s an equal chance it’s going to be his slider that he can throw for a strike.
Even with Gray throwing his breaking pitches as often as he has, batters are still not producing against him. Throwing his fastball less and breaking pitches more could be the key to unlocking the pitcher that was drafted third overall. If I were looking for a starting pitcher right now, I would be targeting Gray both to get him out of Coors and to implement some changes in his approach. The Rockies clearly know they have something here and shouldn’t give Gray up, but unless they’re willing to change their approach with him then he may never reach the potential they saw when they drafted him.
