Kyle Harrison certainly quieted some doubters on Wednesday afternoon in Sacramento. It took almost three months for the lefty to make his debut appearance in a Boston Red Sox jersey, and he looked every bit of what the front office thought they were getting when they acquired him.
While he is going to be a starter down the road, his first appearance came out of the bullpen, where he threw three innings of three-hit, two-strikeout ball that kept the Red Sox in the game.
At 24 years old, Harrison had already pitched in parts of two seasons with the Giants before 2025, making seven starts in 2023 and 24 the following year. By the end of 2023, Harrison was a top 20 prospect in baseball, the No. 1 left-handed pitching prospect in baseball, and the No. 1 prospect in San Francisco's farm system. Since being acquired in the Devers trade, Harrison made 12 starts in Worcester, and fans had been clamoring for him to be called up to help an ailing rotation.
The Red Sox front office acquired Dustin May at the trade deadline (in a panic move when they couldn't get Joe Ryan), then gave both Payton Tolle and Connelly Early their major league debuts before giving Harrison a shot. The team still decided not to use the lefty in his natural role as a starter, instead deploying him as a long relief option.
Kyle Harrison flashed the stuff that once had him as a top prospect in baseball during his Red Sox debut
“Good to go out there and compete. That’s all I was trying to do… just went out there, tried to attack, and get the boys in the dugout as quick as possible.”
— NESN (@NESN) September 10, 2025
Kyle Harrison (3.0 IP, 3 H, 0 ER, 0 BB, 2 K) reflects on his first appearance in a Red Sox uniform 👏 pic.twitter.com/xvSwPEQWMb
Harrison showed what all the hype was about, mixing in five pitches over his three innings, but primarily using his slurve and his fastball. His slurve looked good; while he did allow two hits on it, he also was able to command it well, throwing it for a strike over 70% of the time, getting three whiffs with it as well as five called strikes. There were question marks surrounding his secondaries, but the way he used the slurve today should put some of those away.
With everything Harrison showed against the A's, the organization should be heavily considering putting him into the starting rotation for the rest of the season. While Alex Cora said that they want to keep Garrett Crochet, Brayan Bello, and Lucas Giolito on regular rest, Harrison has a much more proven track record than Tolle and Early. Tolle has been hit hard in his last two outings and has seemingly lost feel for any secondary pitch.
Harrison showed a lot in just a few frames, and with just a few weeks to go in the regular season, the organization should want to see what they have in him before the offseason. Giving him a few starts down the stretch will keep everybody fresh headed into October.