Michael Wacha Starts Anew With the Mets

The Mets signed Michael Wacha to a one-year, $3 million deal with $7 million worth of incentives on Wednesday afternoon, and he ostensibly fills the rotation vacancy left by Zack Wheeler, albeit as their fifth starter. Wacha has exceeded 170 innings only once in his seven-year career, and his 2019 season was discouraging, featuring a 4.76 ERA and a couple of demotions to the Cardinals’ bullpen. On the plus side, he recorded a 3.20 ERA in an injury-shortened 2018 season, and at 28 years old, he could still have several good seasons ahead of him.

Wacha’s fantasy appeal has never been about strikeouts, but he has authored four seasons with a sub-3.50 ERA. In each of those years, he has had low HR/9 ratios and BABIPs, both of which were frequently aided by soft contact rates. Pitching at Busch Stadium helped as well. Over his first six seasons, Wacha had a 3.54 ERA and an 0.7 HR/9 at home,, but a 4.02 ERA and a 1.0 HR/9 on the road. This past season, he was better at home yet again, but neither set of splits was very good. Wacha was abysmal on the road with a 5.30 ERA, and he gave up more than two home runs for every nine innings. At home, his ERA was superficially respectable at 4.07, but he needed to strand 81.7 percent of his baserunners to keep it that low, as hitters collectively put up a .278/.338/.481 slash line against him.

When trying to figure out what went wrong in 2019, it’s hard to pinpoint the exact cause. His average four-seam fastball velocity dropped off from 2018, but it was by less than 1 mph. His strikeout and swinging strike rates were also only marginally lower, and his first-pitch strike rate rebounded from a career-low 53.0 percent to 57.7 percent.

There is a good reason why it’s hard to isolate the source of Wacha’s 2019 decline, because the downturn actually started in 2018. After four straight seasons of throwing strikes at a rate of at least 47 percent, his Zone% in 2018 was just 42.6 percent. That, in and of itself, is not a bad thing, but Wacha has never been particularly good at getting hitters to chase pitches outside of the strike zone. Prior to 2018, Wacha had never posted a walk rate as high as 8.0 percent, but the combination of few chases (27.7 percent O-Swing%) and relatively few strikes shot his walk rate up to 10.1 percent.

While opponents were not chasing out-of-zone pitches much, they were hammering those offerings when they did swing and connect. Through 2017, Wacha had never allowed opponents to record a wOBA on out-of-zone pitches higher than .297, but in 2018, hitters cranked those pitches for a collective .343 wOBA. On pitches outside of the strike zone, Wacha was helping the average hitter he faced produce at a level slightly above that of J.T. Realmuto or Whit Merrifield. Overall, Wacha’s hard-hit rate rose from 30.1 percent in 2017 to 36.6 percent in 2018.

Even though he was allowing much more hard contact than before in 2018, it did not show up in his results. Wacha held opponents to a .249 BABIP and a .221 Avg overall, but his xBA was .279. Hitters slugged a mere .344 against him, but Wacha’s xSLG was .446. While his 2019 results were much worse than those from 2018, there was not nearly as much change in his expected stats (.279 xBA, .490 xSLG). Those who looked at Wacha’s Statcast metrics and expected stats in 2018 likely saw regression coming in 2019, and that is exactly what Wacha gave them.

At least by pitching in another home venue (Citi Field) that favors pitchers, Wacha will have a chance to be, at minimum, a decent streaming option for home starts. If he is going to achieve that much, though, he will need improve his command and control, and those adjustments will need to translate into less frequent hard contact.

Statistical credits: Baseball Savant.