2 reasons Royals can rely on Michael Wacha for stability, 2 reasons they should worry

It is not a stretch to say the Kansas City Royals’ steadiest starter over the past two seasons has been veteran Michael Wacha.

The longtime St. Louis Cardinals right-hander landed in Kansas City after years of one-year stops and has arguably delivered the two best seasons of his lengthy career. He proved his value again in 2025, leading the Royals in games started, innings pitched, and fWAR by comfortable margins.

Heading into his age-34 season, Wacha is under contract for two more years and figures to be the staff’s waterline once again.

He isn’t the ace like Cole Ragans can be when he’s right, and he isn’t as volatile as Seth Lugo or Kris Bubic. He’s the insurance. The kind of pitcher every team wishes it could afford: take the ball every fifth day, keep you in the game, and quietly raise the floor of a rotation. Not sexy, but highly valuable to a competitive club, and if the Royals find October again, he might be the go-to third arm in a postseason series.

There is deserved worry, though. Wacha exceeded expectations in both 2024 and 2025. Can he do it again in 2026? Here are a couple of reasons Royals fans shouldn’t panic and two reasons that concern isn’t coming out of nowhere.

Royals should worry because... Father Time is undefeated.

Justin Verlander. Clayton Kershaw. Max Scherzer. The best pitchers of their generation, and the only three active arms in 2025 with at least 200 wins. Even with all their accolades and Hall of Fame résumés, none of them has beaten Father Time. Wacha won’t, either.

That’s not to say he becomes unplayable the moment he turns 35 later this season. Pitchers are working deeper into their careers than ever. The average MLB pitcher last year was 29.2 years old, the oldest since the same mark in 2005, and it’s been a steady climb since 2021.

We’ve also seen elite late-career examples recently, with pitchers like Chris Sale and Verlander winning Cy Young Awards well into their 30s. But for every one of those success stories, there are a dozen more who start to slip, sometimes subtly, sometimes all at once, as the birthdays stack.

Wacha has traits that can age well, but nobody stays good forever. At some point, the innings and the wear catch up. The only question is whether that moment comes in 2026… or after.

Royals shouldn't worry because... Wacha knows how to win.

Many moons ago, Wacha made his name in St. Louis with October heroics. He won NLCS MVP in 2013, in a postseason where he went 4–1 with a 2.64 ERA across five starts.

He hasn’t matched that exact postseason bar since, but it established something that has followed him everywhere: Wacha is steady, competitive, and rarely overwhelmed by the moment. That trait still serves him well as Kansas City’s rotational barometer.

Pitching wins aren’t the be-all, end-all, but they do reflect durability, opportunity, and a starter’s ability to keep a team in it. Wacha has posted double-digit wins in four straight seasons, and his 48 wins in that span are tied for the eighth-most in baseball.

That’s a meaningful chunk of proof that he hasn’t just survived his career’s bumps, but he’s found a way to keep winning through them.

Add in that he’s performed his best in high-leverage spots (2.51 Clutch, third-best among starters since 2022), and Wacha’s profile looks better than most fans realize at first glance. If the Royals give him even league-average support, his durability and feel for navigating big innings should keep him in the win column again in 2026.

Royals should worry because... The expected numbers were not great.

Expected stats can feel like alphabet soup, but they’re useful context because they help separate what a pitcher controls from what’s influenced by defense, luck, or sequencing.

Royals fans lived this on the hitting side with Salvador Perez last year. His surface line (.236 average, .446 slugging) didn’t look All-Star worthy, but his expected numbers suggested he hit into a lot of bad luck: .272 xBA and .522 xSLG, plus a big gap between his .311 wOBA and .356 xwOBA.

Wacha’s expected profile tells a less flattering story.

His results were strong again and his ERA/FIP put him in a respectable starter tier. Yet, the expected versions of those stats were noticeably worse in 2025.

Statcast’s xERA is essentially xwOBA translated onto the ERA scale, and Wacha’s 4.20 xERA didn’t match the rosier picture of his 3.86 ERA. That kind of gap isn’t new for Wacha, either. His wOBA allowed has beaten his xwOBA allowed every season since 2020, which is either a repeatable trait… or a warning sign that the correction is always waiting.

xFIP was even louder. Wacha’s 4.56 xFIP sat far from his 3.66 FIP, one of the larger disparities in baseball. And when you pair that with the fact that he posted the second-worst SIERA of his career, the “regression is coming” alarm starts to blink a little brighter.

Now, the obvious counter is that expected numbers don’t pitch innings; Wacha does. If he keeps getting outs, nobody in Kansas City is going to hang a banner for xFIP. But if his results slide in 2026, these were the tea leaves.

Royals shouldn't worry because... Wacha still has one elite pitch.

This is where the Royals’ own decision-making matters. During a pregame interview this past season, Dr. Daniel Mack, the Royals’ Vice President and Assistant GM of Research & Development, and the leader of the club’s analytics group, talked about how Kansas City targets pitching acquisitions. One of the reasons the Royals pursued Wacha after the 2023 season was simple: the changeup.

Wacha’s success isn’t only the changeup, but it’s the engine. And even as his arsenal diversified in 2025, the first time since 2022 that his changeup wasn’t his most-used pitch, the pitch stayed nasty. Baseball Savant’s Run Value graded Wacha’s changeup as the third-most valuable in baseball, trailing only Tarik Skubal and Cristopher Sánchez.

It isn’t a pure whiff monster, and the expected numbers still weren’t quite as pretty as the real-world results, but when Wacha needed a stop sign, that pitch remained the one.

It is harder for a starter to ride one great pitch to full-season success, but Wacha's pitchability and that changeup's results mirror nicely with the 2017-2019 stretch from former Royals star Zack Greinke.

Is that to say Wacha will have an All-Star season in store? Likely not, but Grienke since leaving Los Angeles, was one of those players who people constantly thought the wheels were going to fall off. Greinke’s late-career value came from sequencing, feel, and having at least one pitch that never stopped playing. If Wacha’s changeup stays elite, there’s a very real path where he remains useful, and possibly quietly good, through the remainder of his Kansas City deal.