What to expect from Red Sox top pitching prospect Tolle in the Majors

The Red Sox are calling up their most exciting homegrown left-handed pitcher since Jon Lester.

Boston is promoting No. 28 overall prospect Payton Tolle for his Major League debut Friday against the Pirates at Fenway Park, a source told MLB.com's Ian Browne.

Taken in the second round last year out of Texas Christian, the 22-year-old southpaw sports a 3.04 ERA and an 0.99 WHIP over 91 2/3 innings across High-A, Double-A and Triple-A. His 133 strikeouts lead all Red Sox farmhands, while his 36.5 percent K rate ranks third among 288 Minor Leaguers with at least 90 innings in 2025. Mix in a solid 6.3 percent walk rate, and his 30.2 K/BB percentage is second-best among that group, trailing only fellow 2024 pick Trey Yesavage’s 30.8 mark.

Since allowing five earned runs in five innings in his Triple-A Worcester debut on Aug. 10, Tolle settled in at the Minors' highest level with a 3.60 ERA, 17 strikeouts and only two walks over three starts (15 innings). He most recently pitched last Friday against Jacksonville and struck out nine while allowing one run on one hit in five frames.

The 6-foot-6 hurler has pushed for the Majors on the strength of his incredible four-seam fastball, arguably the most effective heater in the Minors this season. Tolle, who began his career at Wichita State, sat 91-92 mph during his one season at TCU but that average velocity has jumped into the 94-96 range with pro instruction. He touched as high as 98.6 during his brief stay in Worcester.

That velocity spike alone would be exciting, but Tolle has shortened the decision window even further with the elite extension in his tall frame. At Triple-A, he’s averaged 7.3 feet of extension. MLB average extension in 2025 is 6.4 feet. For reference, Red Sox closer Aroldis Chapman also averages 7.3 feet of extension, putting him in the 96th percentile in the category for the Majors.

So not only does the fastball come in quicker because of the velo boost, it has a shorter distance to travel because Tolle gets so close to the plate at the point of release. As a result, Boston’s No. 2 prospect can blow the four-seamer by batters regardless of location. The pitch has a 42 percent overall whiff rate this season, per Synergy, and a 40 percent whiff rate in the zone, which would be among the best in the Majors if he carries that to The Show.

That said, Tolle has grown less dependent on his four-seamer over time as he’s tried to complete his arsenal. He relied on the pitch 75 percent of the time with TCU in 2024 and 57 percent of the time between High-A Greenville and Double-A Portland. That usage rate dropped again to 49.5 percent during his short stay in Worcester as he folded in more secondaries. He also works with an 89-91 mph cutter, a mid-80s gyro slider, an upper-80s kick-change and a low-80s curveball.

The cutter and change are more prominently used against righties, and the latter pitch has enough improved drop with the new grip to be an increasingly solid option. For that reason, Tolle has produced relatively even splits throughout 2025 and was even a touch tougher against opposite-side batters at Triple-A, holding them to a .184 average in the relatively small sample.

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While many pitchers struggle to find feel with the MLB ball at Triple-A, Tolle’s walk rate was actually his best with Worcester (3.4 percent). With that combination of stuff and mechanics, he can make for an uncomfortable at-bat by going straight at hitters -- a tactic he should carry to the top level.

There was some speculation that Tolle would join the Red Sox as a David Price-like rookie reliever down the stretch, but this announcement indicates the organization intends to see how he can work as a starter first. That should be his role in Boston, if all goes well, for as extended a time as his stride on the mound.