A Quick Zack Wheeler Update

Late last year, Zack Wheeler got paid. For many, the thought that Wheeler was worth 118 million dollars was a stretch. That’s no knock on the pitcher either: Wheeler had combined for 60 starts and 8.9 fWAR with the Mets from 2018-19, illustrating two years of good health (something that hasn’t always been the case for Wheeler) and strong performance. Still, $118 million is a lot of money for any pitcher.

A subplot of Wheeler’s journey in free agency suggested that whichever team landed him would not only be paying for his established value, but for the opportunity to make use of his hitherto untapped potential. Forgotten were his solid, if not All-Star quality, 2018-19 campaigns while fascination with his pitch characteristics and mix dominated the conversation. Wheeler’s new employer, the Phillies, paid for the chance to tap into that potential.

Early returns have been good. The Phillies, while having gotten off to a slow start, have recently eclipsed the .500 mark, and Zack Wheeler is a big part of that. Through seven starts, Wheeler owns a 2.20 ERA, a 4-0 record, and has pitched in more than 6 innings per start on average. In Wheeler, the Phillies have indeed secured an ace to headline their rotation alongside All-Star and incumbent ace, Aaron Nola. But while the results have been strong on the surface, Wheeler’s underlying statistics and his methods for achieving those results to this point in 2020 have been a bit of an enigma.

Leading up to free agency, when analysts and armchair GMs squinted at Zack Wheeler, the sentiment was that they could see Gerrit Cole. Cole, of course, transformed upon being traded from the Pirates to the Astros. He ditched his sinker for the four-seam, embraced his spin by pitching up in the zone, left his infielders bored for innings at a time, and leaned into FIP-dependent statistics. In making that transformation, Cole went from being dispensable to the Pirates to earning a contract nearly three times as expensive as Wheeler’s. There was reasonable speculation that Wheeler, whose pitch angle, movement, and velocity in several ways closely aligned with Cole’s own, might follow suit. So far, however, while the results have been there for Wheeler, they haven’t come about quite as some might have expected.

Seven starts in, Wheeler has pitched discernibly differently with the Phillies than with the Mets. The four-seam and curveball, which generated his best swing-and-miss percentages with the Mets in 2019, have been turned to more often at the outset of 2020. The heightened usage of those pitches has come at the expense of his changeup, slider, and more drastically, the sinker. Wheeler, like Cole before him, has turned to the four-seam more often relative to the sinker, though he still uses the sinker fairly often. Here are Wheeler’s pitch usages from 2019 to 2020 through 7 starts.

On paper, these adjustments would probably be embraced by so-called analytic types. Wheeler’s four-seam, which ranks in the 90+ percentile in velocity, is being leaned on more often. The Phillies also have Wheeler deferring to his curve as a put-away pitch more often than any other, at 35.5% usage given its whiff rate. This approach seems more streamlined and the end results are there, so what’s the problem?

Put simply, Wheeler’s underlying statistics, unlike those of the traditional variety, have taken some counterintuitive steps. First, Wheeler is interestingly bucking the FIP-reliant trend: he has walked, struck out, and allowed home runs at lesser rates in 2020 relative to 2019. His K/9 figure, at 5.80/9, is the fifth lowest of qualifying starters, between Rockies rotation mates Kyle Freeland and Antonio Senzatela. Next, despite more often utilizing the four-seam, which is more conducive to swings-and-misses than a sinker, his four-seam swinging strike rate is down season over season. Meanwhile, Wheeler’s ground ball rate is at a career high (up to 55.2% according to FanGraphs) and his HR/9 rate is tied (with Framber Valdéz) for fifth lowest in the league, just behind sinker-baller Dallas Keuchel.

45 innings is too small a sample to draw serious conclusions from, but the incongruous start to Wheeler’s Phillies career is an interesting one. Some of the results might be a result of, not pitch mix, but location.

Despite deferring to the four-seam more often in 2020, Wheeler is actually pitching lower in the zone than he has previously in his career. According to Baseball Savant, Wheeler has thrown pitches in the upper-third, or above the belt and outside of the zone 29% of the time in 2020, down from 33% of the time in 2019. Meanwhile, through 45 innings, 33% of Wheeler’s pitches have been below the belt and outside of the strike zone. Yet perhaps the most stark change indicating a novel approach across seasons is captured by Wheeler’s average launch angle. In 2019, according to FanGraphs, Wheeler’s average launch angle was 12.3 degrees. To this point in 2020, that figure is down more than 60% to 4.9 degrees, or seventh lowest among qualifying pitchers. Despite his arsenal, Wheeler is pitching low and getting results typical of a ground ball pitcher.

While Wheeler and the Phillies have seemingly pivoted to embrace a “traditionally” modern pitch mix closer to that of Gerrit Cole, they have bucked the trend of seeking swings-and-misses up in the zone. To this point it has paid off, but whether or not the bottom line results can sustain themselves is a different question. The clearest way to succeed as a pitcher is to master what you can control; presently, Wheeler is not getting the swings-and-misses necessary to do that. That said, one strong start and the K-rate is liable to jump back toward career norms; one poor start and the HR/9 figure could come back down to earth. For these reasons, it is worth keeping an eye on Zack Wheeler.