Back in May, after Corey Kluber was struck in the forearm by a line drive, fracturing his ulna, I remember combing through the Cleveland Indians’ upper minor league rosters in an effort to find a promising replacement. My methodology was simple, maybe to a fault: aside from the occasional blurb, written by whatever prospect analyst I could find, my entire process was to “scout” stat lines to find the most productive players so far. This isn’t the worst method; after all, most MLB stars were also standouts in the minor leagues. Still, there’s only so much one can learn about how a pitcher pitches by looking at his strikeouts and walk percentages, and his rate of inducing ground balls, and his ERA. How a player accomplishes something is as important to understand as the accomplishment in the first place, and all I had was the latter. Because of the lack of information and footage of minor league baseball, it was the best I could do. When I combed through the upper levels of the farm system to find a replacement for Corey Kluber, the best name I could come up with was Zach Plesac.
I hadn’t heard of Plesac before, but his stat line jumped off the page. He just dominated the competition in Double-A to begin this season. In 37.1 innings over six Akron starts, he allowed four runs. He struck out 34 batters, and only walked six. In Triple-A, his command of the zone was even more impressive. Over 20 innings with the Columbus Clippers, Plesac struck out 22 and allowed five runs while walking one batter—one! You’d think the Indians would have to seriously consider calling up a high minors pitcher who’s walked 3.3% of the 213 he’d faced, but just last season, another young pitcher had an even more impressive, seemingly preternatural command of the zone, and it took the Indians what felt like an eternity to give him a chance over uninspired, but reliable Quad-A arms like Adam Plutko. Indeed, Cleveland’s history made me think we’d have to endure a summer of Cody Anderson and Plutko starts before we got a glimpse of Plesac. But here we are, 60% of the starting rotation on the shelf, and Zach Plesac’s starting at home Friday night against the Yankees.
Minor league dominance, control of the strike zone, and a relatively quick rise to prominence are not the only characteristics Zach Plesac and Shane Bieber share. During Bieber’s stint at the big league level last year, he relied on his 93 MPH running fastball 57.3% of the time; in Plesac’s two starts, he’s mixed in his 94 MPH running fastball 59.9% of the time. Maybe it’s not surprising to learn that in 2018, Shane Bieber’s opponents walloped his fastball; opponents racked up a .871 OPS off the cheese while whiffing under five percent of the time. When you throw the same, non-elite fastball as often as he did, even with sterling, elite command, Major League batters will figure out how to hit it. Bieber, by the way, is throwing his fastball 21% less frequently this year—it’s still his pitch that gets hit the hardest, but much less so than last season.
So how have batters fared against Plesac’s fastball, which he throws nearly three-fifths of the time? On the surface, it appears that Plesac has stymied them—look deeper, and you’ll find a different story. First, on the plus side, the fastball has garnered swinging strikes over 10% of the time, a decent number. When he locates his above-average fastball, with the late run, it’s a pretty nasty looking pitch; Eloy Jimenez can attest.
If Plesac has worried the batter that a change-up, his best pitch, could be on the way and he locates the fastball well, he’s liable to produce plenty of swings like Jimenez’s above. The problem is, it’s difficult to trick Major League multiple times with only two reliable pitches. After one at-bat, opposing hitters likely have seen all of the pitches Plesac will throw to them. And when three-fifths of the pitches are fastballs, you’d better believe hitters are sitting and waiting for one to drive. Yes, batters have so far hit well below-average against Plesac’s fastball, but two games’ worth of one pitch just isn’t statistically reliable. This Mookie Betts flyout would have been a homer in most ballparks. Here are two more fastballs that got mashed right at infielders. Zach Plesac’s fastballs have been productive so far, but the process lags behind the results, especially when you consider where he’s located the pitch:
I don’t expect Plesac to continue to have this much success while using his fastball so frequently and locating it so hittably, and that’s a problem.
When Shane Bieber was called up, he threw predominantly fastballs despite reports of two quality breaking balls in his repertoire. Perhaps Bieber was encouraged to rely on his fastball to more slowly unveil his pitch mix to the league, or maybe he was coached to begin his career throwing the pitch he was most comfortable with the most often. More likely, it’s for some reason I can’t even fathom. The point is, Bieber had a quality, three-pitch arsenal even then, and now he’s up to four pitches.
Zach Plesac, on the other hand, really only has the fastball and the change-up. Unfortunately, there just aren’t many successful major league starting pitchers who rely on two non-knuckleball pitches. Those few that are successful, like James Paxton or Luis Severino, they throw 99 MPH. Plesac’s stuff is good, above-average stuff—but it’s not Paxton, and it’s not Severino. As impressive as the change-up looks at times, if Zach Plesac is going to be, long-term, a successful Major League middle-of-the-rotation starter, he’s going to need to throw his slider or his curveball more often. Luckily, his employer does also employ a certain pitcher who created a new slider in a single offseason; perhaps it’s Trevor Bauer’s capacity as a pitching coach, not a player, that will discourage the Indians from moving him at the trade deadline. Whether it’s Bauer or somebody else, Plesac’s future in the rotation largely depends on whether or not someone can teach him how to spin one.