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Is Michael Wacha’s solid start a reality or a mirage?

Michael Wacha has been very good in the Red Sox’s rotation, but some disquieting metrics lay below the surface of his strong start to the 2022 season. 

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Boston Red Sox v Toronto Blue Jays Photo by Mark Blinch/Getty Images

It’s been quite a while since Michael Wacha was an above average pitcher. The last time the righty finished better than average with both his park-adjusted ERA and park-adjusted FIP (i.e. ERA- and FIP-) in a single season was when he was with the St. Louis Cardinals. Since then, he’s pitched for four different teams, including the Red Sox this year, and for the most part he’s been far from effective. It made the Red Sox’s signing of the 30-year-old veteran with more than 1,000 innings on his arm this past winter seem a bit puzzling for a team that needed more than just depth.

However, as we near the end of the first full month of the 2022 campaign, Wacha has defied his recent results and been in the conversation for the title of the Red Sox’s best full-time starter. Recent outings from Nathan Eovaldi and Garrett Whitlock have been more dominant than any of Wacha’s, of course, but Wacha has been more consistent than Eovaldi and has been a member of the rotation for the whole year, while Whitlock has just recently joined the rotation and is only making short starts. In fact, based on both ERA- and ERA+, among full-time Red Sox starters, Wacha is easily at the top of the depth chart. So, has something changed or is this just a small sample mirage?

The argument for the former is based on Wacha’s pitch mix, including what, where and how well he’s throwing it. Wacha has spent a large portion of his career relying on three pitches while dashing in a couple others to keep hitters off-balance. Those three favored offerings have generally consisted of his four-seam fastball, changeup and cutter. In 2022, however, he has simplified his arsenal even more, by beefing up his changeup usage (which continues a recent trend) and cutting (pardon the pun) into how much he uses his cutter. In 2021, he threw 36.1 percent fastballs, 29.4 percent changeups and 24.9 percent cutters. Those numbers have morphed to 38.5 percent, 32 percent and 14.2 percent, respectively, this season.

While Wacha has had similarly low cutter usage before, it has usually been because he was throwing his fastball way more. For example, in 2019, he only threw his cutter 15.5 percent of the time, but he was at nearly 50 percent with his fastball. Now he’s almost evenly distributing his fastball and changeup usage while letting his cutter take a back seat. Relying on a strategy that boils down to throwing the ball hard and soft depending on the situation is a simple and perhaps antiquated one, but it’s really paying off for Wacha because of how effective each pitch has been. His changeup has been particularly lethal, ranking ninth among MLB pitchers with at least 20 innings pitched in changeup pitch value. In addition, despite less than dominant velocity, Wacha has the 11th-most valuable fastball in MLB among that same group of pitchers.

The fastball-changeup reliance isn’t just showing up on the pitch value charts either. It’s also leading to strong results in terms of run prevention. Wacha has an ERA of 1.77 right now, and although that is leagues ahead of his expected ERA (3.33), it’s not like the latter is particularly bad. In fact, it’s very good. Speaking of expected things, Wacha’s expected batting average against ranks in the 73rd percentile, and he’s above the 50th percentile in expected slugging.

The question is: How long can a solid fastball/changeup foundation work? So far, so good, as Wacha is coming off his strongest start of the year, allowing just one earned run over six innings against the mighty Toronto Blue Jays last week, but if we dive deeper into his numbers, the outlook becomes much more ominous. Just look at his Baseball Savant page:

Baseball Savant

That is an awful lot of blue for someone with Wacha’s surface-level production. As the chart shows, even though his fastball has been good this year, it doesn’t have a ton of velocity or spin. In addition, he isn’t getting a lot of swings and misses, with his chase, strikeout and whiff rates all falling well short of even the middle of the road. That means opponents are making a lot of contact, and even if they aren’t barreling the ball to an astounding degree against him, Wacha’s average exit velocity is concerning. All that contact looks even worse when examining his batting average on balls in played allowed, which currently sits at an astounding .154. For now, a lot of those batted balls are turning into outs, but what happens when his BABIP returns back toward normal? If Wacha were inducing a ton of weak contact, it would be one thing, but with a well above league average exit velocity (91.2 MPH) and league average marks in hard hit rate and barrel rate, Wacha isn’t doing that exactly.

To make matters worse, while Wacha is avoiding hits, he’s not avoiding walks. His 11.3 percent walk rate right now would be a career-high if it held for the whole season and it ranks in only the 29th percentile in MLB. Wacha still has a sub-1.00 WHIP despite all those free passes, but if more hits start piling up, that won’t last nor will his positively preposterous 92.6 percent strand rate. Of course, if Wacha could cut his walks as a few more hits fall, then he perhaps could split the difference and maintain some of the success he’s had, although that is a bit of an oversimplification and not entirely likely based on his recent body of work before 2022.

So, what does this all mean for the rest of Wacha’s season? It could mean very little. He has only made four starts and logged 20 13 innings, which is still a relatively small sample. We’ll obviously learn more and be able to make more certain statements about his performance as the season goes on. At this stage, however, as much as Wacha has been good to start his Red Sox career, there is far too much going wrong under the surface to feel confident that the Red Sox really found a diamond in the rough.