Muñoz's improved changeup an unhittable weapon

This story was excerpted from Daniel Kramer’s Mariners Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox. This edition was written by MLB.com reporter/researcher Theo DeRosa

Andrés Muñoz’s up-and-down season hit another low on Sunday with a blown save against the Athletics. But there’s a reason for optimism for the Mariners' closer moving forward: the further development of what might be one of the nastiest pitches in MLB.

More and more in recent weeks, the right-hander has been throwing a changeup that hitters simply can’t touch. In 19 at-bats ending on Muñoz’s changeup this season, opponents are 0-for-19 with 17 strikeouts.

“I think it’s a pitch that can be unhittable,” Mariners manager Dan Wilson said.

So far, it has been. On 29 swings against the changeup, hitters have swung and missed 24 times for a ridiculous 82.8% whiff rate. The pitch has a minuscule .012 expected batting average and a .013 expected slugging percentage, backing up just how good it has been.

But for much of 2026, it wasn’t a major weapon for Muñoz. He focused on his slider, sinker and four-seam fastball, throwing the changeup just 3.5% of the time through the end of July. Since the start of August, that number has risen to 14.8%.

Why the increase? Credit Cal Raleigh and the Mariners’ catchers, who have seen how effective Muñoz’s changeup can be and have been calling it more often.

“I feel a lot more comfortable with that pitch right now,” Muñoz told MLB.com. “I trust a lot in the catchers. They can tell me when it’s a good pitch. Even if I am missing some of the spots that I want to hit, they know when that pitch has good movement, and that’s the reason why they started calling them more.”

Muñoz has been ramping up his changeup velocity throughout the year, gaining nearly 3 mph on the pitch from the start of the season to September. Over the past two months, it’s averaging 93.5 mph, looking for all the world like the righty’s 99.7 mph four-seamer -- until it dives below the zone with 4.2 inches more vertical drop on average than comparable changeups.

“The best thing for a pitcher is to throw different pitches that look the same,” Muñoz said. “As soon as that thing looks like a fastball and then drops, I think it’s a great pitch.”

With that kind of elite velocity and movement, there’s little need for Muñoz to throw his changeup in the strike zone for it to be effective. Only four of the 62 changeups he’s thrown all season have been in the zone, with two just dotting the outside edge.

“As long as you can start it in the zone and let it run out, it’s a really tough pitch to lay off of,” Wilson said.

One of those two offerings was the only changeup Muñoz has thrown all season to a right-handed batter: an 0-1 pitch right down the middle to surprise the Astros’ Jose Altuve during a May 11 game in Houston.

Otherwise, Muñoz has exclusively featured the pitch against lefties, but he’s willing to mix things up.

“I’d have to look at that,” Muñoz said. “But I am up to throwing it to righties. That would depend more on the catcher, what he thinks about this hitter, or things like that.”

After all, Muñoz’s electric changeup has come a long way since making its debut during 2025 Spring Training. The pitch started as a “kick-change,” with Muñoz’s middle finger raised off the ball to create horizontal spin. That’s no longer the case this season; Muñoz said he couldn’t control the pitch very well.

Throughout 2026, Muñoz’s changeup grip and delivery have remained consistent, but he has ramped up the intensity and the velocity to great effect.

“When you start throwing something new, you are a little bit more concerned about, ‘Is this the right pitch to throw?’” he said. “With time, you start to throw it more and get more comfortable with it.”

Muñoz sure looks comfortable with his changeup now, and that’s a scary proposition for opposing hitters.