This story was excerpted from Alex Stumpf’s Pirates Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

OAKLAND -- When looking at Hunter Stratton’s Minor League career, the last three seasons before his promotion to the Pirates’ bullpen tell a story about what might be the most important pitch in his arsenal.

The first is 2021, the year when he initially burst onto the scene as a legitimate Major League prospect. After converting to the bullpen in '19, Stratton came back from the canceled '20 Minor League season with mid-90s heat, striking out 70 batters over 49 innings, to rise from Double-A Altoona to Triple-A Indianapolis in what he thought was the best year of his career to that point.

“I felt strong,” said Stratton. “I felt through the ball. I had all the conviction in the ball.”

The Pirates were encouraged, but they suggested a change: More sliders, fewer cutters. Stratton has two fastballs (a four-seamer and a sinker) and two breaking pitches (a cutter and a slider). The team thought more sweep on his breaking ball would result in more whiffs. It didn’t, and Stratton followed his best Minor League season with his worst, posting a 5.71 ERA in 2022.

Searching for that 2021 feel again, Stratton brought the cutter back last season and posted quality numbers (3.99 ERA in 56 1/3 innings) with Indianapolis, culminating in a cup of coffee in the Majors in September. After earning a spot on the Opening Day roster, the rookie right-hander has impressed thus far, recording a 3.07 ERA with 15 strikeouts over 14 2/3 innings. He also boasts a 35.8% whiff rate, which ranks in the 95th percentile.

That whiff mark starts with one particular pitch.

“I think the cutter plays into it,” Bucs manager Derek Shelton said. “I think [he’s] using the repertoire, and using the cutter now has enhanced that.”

All three of Stratton’s primary pitches have a high whiff rate (28% for the cutter, 33.3% for the four-seamer and 70.6% for the slider in a limited sample size), but the cutter is his go-to. He’s thrown it 44.3% of the time, and while he has been dinged for a couple of homers on it early, it’s how it plays off the rest of his stuff that makes it so effective.

Originally, the cutter was a “get me back in the zone” pitch for Stratton. Hitters are sitting fastball, and his slider can get too big to try to locate in the zone too often, as he saw in 2022. As Stratton continued to use the cutter, he started to notice it was a great pitch to get some ground balls, steal some strikes and shatter some lumber.

“'That’s always fun, to get a broken bat,'” Stratton recalled thinking to himself. “'Let’s up the usage of it.'”

The end product was a pitch mix that centered around the cutter. Stratton throws each pitch from the same arm slot, and they all get good spin (roughly 2,600 rpm for each offering). That means they all move, and in different ways.

The slider is almost all horizontal movement, averaging 10.9 inches of break. According to Baseball Savant, that’s 5.1 more inches of movement compared to the average pitch from a similar extension point and speed. The four-seamer is all vertical movement, averaging about 13.7 inches with just a little bit of natural cut (2.3 inches of horizontal).

The cutter is the median pitch. It gets above-average horizontal movement (0.5 inches more), allowing Stratton to throw backdoor cutters to left-handed hitters or force right-handers to guess if the pitch darting outside is a cutter that will catch the zone or a slider that will keep falling. It also gets 21.4 inches of vertical movement -- one more than average -- which can create awkward swings for hitters trying to identify how much cut that 90-something-mph offering is going to have, all while it is also giving the illusion of rising.

“They still see the cut spin, so sometimes it’s an auto-take for a strike,” Stratton said.

The cutter may not have the highest whiff rate of his pitch mix, but it’s more than just a way to get back in the zone. It’s a way to set up an at-bat.

Stratton is just starting to get his feet wet in leverage spots in the Majors, and depending on who is available on any given day, he could be used as anything from a multi-inning guy to the person Shelton will turn to in strikeout situations. Stratton isn’t buying into reliever roles, so he welcomes each opportunity.

“I know what I have to do to be successful at this level,” Stratton said. “I’m just trying to do that every time.”