Wednesday brought the exciting news of Zack Wheeler’s 5 year, $118 million signing with the Philadelphia Phillies, and with it a multitude of pieces comparing his stuff to the very best pitchers in the game today: Gerrit Cole and Jake deGrom. These are the 2 most prominent aces in the league; comparisons to them should not be taken lightly. Yet Wheeler warrants them, as his stuff is that good and he’s flashed that level of ability throughout his career.
First, the stuff: he had the 4th highest average fastball velocity in all of MLB last season, behind only Cole, deGrom, and his other former teammate Noah Syndergaard. His slider velocity is topped only by deGrom’s. He has great control, walking a career-low 6% of opposing batters last year compared to deGrom’s 5.5% and Cole’s 5.9%. He doesn’t serve up home runs, sporting a HR/FB% of 10.9% in 2019; Cole was 16.9% and deGrom was 11.7%. He was in the 90th percentile of pitchers in average exit velocity allowed and the 82nd percentile in hard contact against. deGrom was in the 93rd and 88th percentiles, respectively, while Cole was in the 66th and 57th.
|Average fastball velocity||BB%||HR/FB%||Average exit velocity against percentile||Hard contact against percentile|
Zack Wheeler, then, has pitch ability on par with the best 2 pitchers in MLB, walks roughly the same amount of batters, surrenders home runs at an equal or better rate than those 2, and induces weak contact at a similar level to deGrom and a superior level to Cole. So why hasn’t Wheeler’s overall performance placed him in the same tier of pitcher? He’s currently thought of as a very good #3 starter or a solid #2 starter; why isn’t he an ace? What does he need to do to make The LeapTM and join the ranks of the elite pitchers that his skill set seems to indicate he should?
To answer these questions it may be helpful to examine how Gerrit Cole and Jake deGrom became Gerrit Cole and Jake deGrom. Before Houston acquired him, Gerrit Cole was a talented and largely very good pitcher for the Pirates, even making the All-Star team and finishing 4th in NL Cy Young voting in 2015. However, he wasn’t the Gerrit Cole we know today, the fire-breathing leviathan sent to take the souls of hitters everywhere and strike out 300 batters a year. The most obvious change that Cole made once the Astros pitching coaches got their hands on him is that he mostly abandoned his sinker and primarily became a 3-pitch pitcher with his 4-seam, curve, and slider making up over 90% of his pitches in 2019. Compare this to 2017, his final year in Pittsburgh, when he threw all 5 of his offerings at least 10% of the time. It’s also worth noting that Gerrit Cole’s K rate and walk rate from his last year with the Pirates line up nearly exactly with Wheeler’s K rate and walk rate from 2019 with the Mets:
2017 Gerrit Cole K%: 23.1 BB%: 6.5
2019 Zack Wheeler K%: 23.6 BB%: 6.0
The other major change Gerrit Cole made when he joined the Astros was that he began to attack hitters at the top of the strike zone far more aggressively, particularly using his 4-seamer to devastating effect. This has become his biggest weapon, and when you think of Gerrit Cole the image that you probably conjure is a hitter striking out by missing a 99-mph fastball at the top of the zone. In 2017, Cole threw his 4-seam 410 times in 2-strike counts; by 2019, that number had increased to 656. Wheeler threw 548 such pitches in 2019, so pitch selection isn’t necessarily the issue here. Where he placed those fastballs in 2-strike counts, however, could make all the difference.
As mentioned before, Wheeler placed in the 90th percentile in average exit velocity against this past season. This means that he was exceptional at inducing weak contact, often by throwing his pitches lower in the zone when he was ahead in the count. Here is his 4-seam fastball placement in 2-strike counts, courtesy of Brooksbaseball.net:
And here is Gerrit Cole’s fastball placement in the same situation:
As you can see, there is a vast difference in the pitchers’ approaches. Cole looked to finish batters off by “climbing the ladder” and overwhelming them with the pure speed and rise on his fastball. Wheeler, by contrast, looked to induce soft contact by pitching in the lower half of the zone. This strategy is fine on its own but renders the pitcher more vulnerable to bad luck on balls hit in play and makes the pitcher’s performance more dependent on the ability of the fielders behind him. Both factors likely hurt Wheeler last season when opposing hitters had a .311 BABIP against him and he played in front of a Mets defense that ranked in the bottom 5 in nearly every defensive metric. To become more consistently dominant, Wheeler should emulate Cole and trade some of that weaker contact for more whiffs at the top of the zone, becoming a more traditional power pitcher. “Throw high fastballs” is not a recipe for success for everybody, but when a pitcher can touch triple digits like Wheeler can it becomes a tool to blow away even the best hitters. Wheeler has done this before, but never consistently. Here’s an example of how overpowering this high heat can be, against the Phillies’ very own Roman Quinn:
Given the Phillies’ organizational emphasis on this philosophy in 2019 – even to the detriment of some of the younger pitchers, one might argue – it feels safe to assume that Wheeler will be adding this arrow to his quiver in the years to come to a much larger extent than he has thus far in his career.
Jacob deGrom is the other ace that Wheeler has drawn comparisons with, and for good reason; deGrom and Wheeler both feature heaters that routinely hit 97+ and they boast the 2 fastest sliders in the game. It’s a natural comparison to make, especially given that they’ve worn the same uniforms for their entire careers to this point. How did Wheeler’s ex-teammate make the final leap from very, very good to back-to-back Cy Young winner, and can Wheeler glean any lessons from it?
deGrom was a very good pitcher before the 2018 season, having won NL Rookie of the Year in 2014 and making the All-Star team in 2015. But in 2018, he reached an entirely new level, having one of the most dominant seasons of all-time while posting a 1.70 ERA over 217 innings and winning the Cy Young award. He then followed that up with another Cy season, pitching to the tune of a 2.43 ERA despite the offensive explosion across baseball caused by the juiced ball.
Much like Cole, deGrom’s ascension can be directly correlated to him consolidating his pitch usage to his 3 best pitches; in his case, he became a 4-seam, slider, and changeup pitcher and eschewed his sinker and curve to an increasing extent in 2018 and 2019. After throwing those 2 pitches a combined 816 times in 2017, he dropped to 550 times in 2018 and finally just 127 times this past season. He increased his slider usage over these 2 seasons, to the point where he threw the pitch 32% of the time last year. Hitters were helpless against the devastating breaking pitch, hitting only .192 against it with a .222 WOBA.
Wheeler’s slider is not quite as lethal, but still limited batters to a .275 WOBA. He also doesn’t generate quite as many whiffs with his slider as deGrom does, once again mostly inducing weak contact with it more often than not. He does have a breaking pitch that generates a similar percentage of swings-and-misses to deGrom’s slider, however: his curve. This is Wheeler’s most under-used pitch; he only threw it 10% of the time in 2019. Yet it’s the pitch that batters consistently whiff on whenever Wheeler chooses to use it. Look at the whiffs per swing that he’s generated with the pitch throughout his career and how that compares to deGrom’s slider in his career:
Those rates at the bottom of the zone rival exactly what deGrom can do with his slider: consistently generate swings-and-misses with his best breaking pitch. The obvious difference is that deGrom uses his slider a lot more. Wheeler should consider doing the same with his curve, which is far too good of a pitch for him to only use 10% of the time, as he did in 2019 and 2018. Look at how devastating this pitch can be:
This new plan would have the added benefit of tunneling nicely with the high fastball approach that he can take from Cole, giving hitters even more to think about when facing him. Having the threat of the curve on their mind makes it even more difficult to catch up to 99 at the top of the zone.
Zack Wheeler is already very good. He has been worth 4.7 and 4.2 fWAR the last 2 seasons. That combined total of 8.9 WAR is tied with the Phillies’ own ace of the staff, Aaron Nola, and is the 10th most in all of baseball. If he doesn’t make a single change to his approach and pitches the same as he has, he’ll still be worth the contract given to him and be a solid #2 starter. But perhaps by throwing more high heat at the top of the zone and increasing how much he throws what could prove to be a wipeout curve (and subsequently throwing his sinker somewhat less) Wheeler could improve and join the ranks of the truly elite pitchers at the top of the game. If he can add to his 2019 K rate of 23.6% and get closer to deGrom’s 31.7% – never mind Cole’s record 39.8% – then he can become a dominant pitcher and form a 2-headed monster at the top of the rotation with Nola. All the ingredients of an ace power pitcher are there, he just needs to take the last step.