Mariners pitchers keep adding pitches — and it’s more than a ‘side project’

Feb 26, 2025, 5:02 PM | Updated: 5:03 pm

Mariners Insider, Seattle Sports

One of the more interesting items on the spring training bingo card is the new pitch. Each spring, multiple Seattle Mariners pitchers – starters and relievers – show up in camp with something new. It could be the latest and greatest, or perhaps an oldie that was viewed to be the missing piece of a pitcher’s repertoire.

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In the past, the new pitch often turned out to be much ado about nothing as most would be left in camp. In recent Mariners camps, however, we have seen new pitches brought north and put into games that count. We’ve seen pitches developed in-season, something that was virtually unheard of in the past. New pitches are something to take note of, and, when it comes to the Mariners, are sometimes hard to keep track of because of the sheer number.

“We call them ‘side projects,'” said Trent Blank, a major league coach and the Mariners’ director of pitching strategy. “We have been saying it so much that we don’t want to say it anymore. We are trying to come up with something new like leisure activities, hobbies for the week.”

Blank estimates there are 13-15 new pitches in camp this spring, a number that is actually down from 2024. Whatever they call them, there is no question they have played an important role in the success of Mariners pitching.

The splitters added by Logan Gilbert in 2023 and Bryce Miller in 2024 are probably the most notable to date as far as pitches that have graduated from camp to the season. Those pitches were developed over offseasons, tracked by the Mariners’ coaches. Other pitches, including the Andrés Muñoz kick changeup that’s turned heads in the last week, have been thought up and unveiled in a matter of days, developed more on the fly.

It is a sight Blank is getting more accustomed to seeing.

“Logan Gilbert invented something yesterday I haven’t seen,” he said. “It’s more of a kick fastball.”

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The changes in repertoire coming fast and furious can be hard to keep up with.

“We get messages from Pitch Info and these third parties that kind of help us manage our information, and they are just like, ‘What’s this? What’s that?’ Some of these pitches I know about. Some of them I don’t know about,” Blank said.

Wednesday afternoon, the pitch data services were playing catch-up again as George Kirby debuted the cutter he worked on this winter. He threw two cutters in his start against the A’s, one going for a line drive flyout, the other a swinging strike. Both were initially misidentified on MLB Gameday and Baseball Savant before being corrected later in the afternoon. It’s a pitch that should give Kirby something he can throw in on the hands of lefty hitters and help keep them off the high fastball.

Kirby bringing a new pitch into camp is nothing new as he is no stranger to tinkering and adding pitches. He could almost be pointed to as the godfather of quick adds for Mariners pitchers, adopting the Robbie Ray two-seam fastball in a couple of bullpens in 2022 and taking them into games. Then there is the mad scientist, Gilbert, who is running out of Pitchcom buttons.

“He’s discovering new frontiers and pitches,” Blank said. “Everybody’s been throwing the kick changeup, that’s been popular. Then he walked up to me one day and was like, ‘Hey, I’m gonna hold it like this – index and middle finger only – and I’m just like, is that a breaking ball? ‘Cause I’ve never seen it. Usually with the kick change you’ve got all the fingers on the ball. And he threw it and it came out his hand in a different way than we’d never seen. And I was just like, I don’t even know what to call that so.

“Right now it’s a side project.”

Method to the madness

Side projects have their time and their place. There is a balance, and there are strengths that Blank and pitching coach Pete Woodworth do not want their pitchers to get away from. Still, there is the freedom to try, and that is encouraged as the creativity and flexibility is actually part of the Mariners’ pitching program, according to Blank.

“What you’ll see in our throwing program is guys are going to throw from different slots,” he said. “They will spin the baseball in different ways. You’re going to see guys who are throwing to different targets. They are exploring the spectrum of throwing and it’s going to look chaotic at times, but it’s actually got a purpose behind it. And that purpose is to keep guys really adaptable and challenge them at the same time.”

It is these few minutes of the throwing program that allows the Mariners to do things in-season that you would rarely have seen in the past at the major league level. Before, a pitcher was what a pitcher was on Day 1 of the season in terms of repertoire, but Mariners pitchers are better able to make adjustments or changes should the need arise. It is likely these exercises have also sparked creativity and resulted in a number of side projects, something that for the Mariners is much more than just a spring training bingo card spot.

“It’s sick when someone just creates some gross pitch that you wish you had too,” Kirby said. “So yeah, it’s just fun being around everybody. Everyone’s so good.”