With the Mariners’ announcement that Logan Evans will miss the entire 2026 season with UCL surgery, the Marinersphere is debating who will be the new sixth starter. Kade Anderson’s not ready, and Mariners fans are all too familiar with the flaws of Emerson Hancock and Dane Dunning. So a lot of eyes have turned to recent waiver claim Cooper Criswell.
A 6’6” righty sidearmer, Criswell throws a sinker-cutter-changeup-sweeper mix. He’s been tried in both the rotation and the bullpen, and was most recently
a starter with Boston. But he’s out of options and a popular waivers target, so if he’s going to stay in the organization, he needs to be on the 26-man roster rather than stretched out in Tacoma.
If there’s an injury, you could stretch him out in MLB within four or so outings. But if the Mariners plan to make adjustments—and they should—it’d be hard to know how those changes play into his ability to get through the batting order more than once. So for now, it’s best to evaluate him as a reliever.
That puts him in what Lookout Landing affectionately calls The Pile, the collection of arms amassed to spend the spring battling it out for a role in the bullpen. Out of this year’s Pile, Criswell’s my pick for a success story.
My vision is straightforward: Criswell has elite stuff on his sweeper and changeup, but he’s locating them like a contact manager instead of a strikeout pitcher. Adjust the aim on both, throw the sweeper way more often, and cut back on his terrible sinker. Do that, and he could be the next poster child for the Mariners Pitching Factory.
His sweeper ought to be his moneymaker. It comes in with a hellacious 20 inches of horizontal movement; that’s three inches more than the width of the plate. FanGraphs’ Stuff+ metric rates the pitch in elite territory. Yet hitters crushed it last year to the tune of an .875 SLG. I wouldn’t read too much into that though. He only threw 31 sweepers in MLB last year, and just 8 were hit into play. He threw 200 sweepers in AAA, and hitters only managed an xSLG of .284 with a whiff rate of 42.6%, the stats of a wipeout pitch. I see a lot of Penn Murfee here—another sidearming piece of org depth whose sweeper turned him into a viable reliever.
Still, it’s concerning that Criswell didn’t put up positive marks by run value on the sweeper in 2023 or 2024 either, when the samples were bigger. I suspect the issue here was his location. Sweepers with this kind of movement that land in these locations are attempts to steal strikes or pick up weak contact, starting in the righty batter’s box but landing in the zone.
That’s the wrong strategy for a big-movement sweeper; sweepers are supposed to be whiff-generators. Start it in the zone and let guys flail at it while it sails into the lefty batter’s box. Compare Criswell’s locations with those of the swings and misses on sweepers thrown by righties across the league:
This can be a swing-and-miss pitch for Criswell, and if it becomes one, that would warrant throwing it more often than he ever has before. He’s never topped a 30% usage rate with it over a meaningful sample. But relievers with a wipeout sweeper can get away with almost double that.
But it wouldn’t cure all that ails Cooper Criswell. Sweepers come with dramatic platoon splits. Even Paul Skenes only throws his to lefties about a third as often as to righties. For Criswell, that’s where the changeup can come in, a pitch famous for neutralizing platoon advantages. It’s another pitch with extreme shape, dropping 7-8 inches more than comparable ones, and he commands it well. But like the sweeper, he leaves it in the zone too often, as if he hopes guys will get on top of it and hit a weak ground ball rather than aiming it below the zone to tempt hitters to swing over the top of it.
Why would Criswell locate his sweeper and changeup the way he does? My guess is that it’s all because his fastball is bad. He throws a sinker with only average run and below average ride. But worst of all, it averages just 89 mph, which his height and extension only bump up to a perceived velocity of 90. And his height also counteracts his sidearm slot, so he doesn’t get the rising fastball illusion that sidearmers often generate (VAA, for the nerds). This pitch stinks.
That brings me to my guess about his location. I suspect that somewhere along the way, he got it in his head that to survive as a guy with a sub-90 fastball, he had to become a contact manager. But that’s just not true, not if you’ve got a good cutter and a couple wipeout pitches.
Fortunately, Criswell does have a good cutter. By run value, it’s consistently graded out as his best pitch, and while it’s on the slow side, it should be enough of a foundation for the sweeper and changeup to play off of. And he already started trusting it a bit more last year, both in MLB and AAA, up to about 25%. But he could throw it even more often than that, replacing the sinker as his primary set-up pitch.
To be sure, you can’t abandon fastballs altogether unless your cutter is in Rivera/Jansen/Clase/Burnes territory, which Criswell’s is not. But you can adjust the mix to favor the cutter.
So my prescription happens to line up with adjustments that the Seattle Pitching Factory excels at.
First, shift the pitch usage to something more like: 40% sweepers (mostly to righties), 30% cutters, 20% changeups (mostly to lefties), 10% sinkers. That actually dials the changeup down from what he did last year. But as a reliever, the Mariners can pick their spots to use him mostly against righties; as a starter/long reliever, opposing managers could use their lefty bats against him.
And second, go ahead and chase some whiffs, even soft-tossers are allowed. Aim the sweeper to start in the zone and sail low and outside; aim the changeup just below the bottom rail rather than just above it. Given his command, those are doable changes.
Watch the sweeper usage and location during Spring Training. If you start seeing more sweepers, especially ones finishing in the lefty box, don’t be surprised if he goes from my ’26 Pile Pick to Seattle’s ’26 Pile Payoff.
