Player review: Kyle Harrison

2025 stats (both SFG & BOS): 11 G 35.2 IP, 4.04 ERA / 3.72 FIP, 38 K, 14 BB, 4 HR, 1.27 WHIP, 39 GB%, +0.5 fWAR, big part of the Rafael Devers trade

Usually, these year end player reviews focus on what a player did for the Giants, but it’s tough to talk about Kyle Harrison’s season without mentioning everything after they traded him to the Red Sox. One of the team’s former top prospects had pitched himself into a ditch and looked to be stalled developmentally — on the verge of being declared a bust, even — insofar as the top of the rotation aspirations the previous front office and scouting department had. The looming question heading into the season was, “Is Kyle Harrison actually a reliever?”

That notion doesn’t make its way into the general conversation without some support from industry folks, which means Harrison caught wind of it at some point. He was drafted and touted as a potential top of the rotation type and didn’t make the leap from high school to the pros without that thought being front of mind. And yet when you’ve got knowledgeable folks like Eno Sarris talking like this the moment after he’s traded —

— it stands to reason that Harrison heard whispers about his past, present, and future for several months, and after the trade went down, the dam broke. This headline from FanGraphs — with Harrison the lead image no less — is painful.

How Quickly Should You Change Your Mind About Elite Pitching Prospects?

It’s the kind of pressure most of us don’t experience in life or have and only had to suffer it briefly because we couldn’t handle it. A 23-year old ought to see his whole life in front of him. Nothing set in stone, free to discover and become his own person. And yet, because most of his life to that point has been baseball, “I’m a good pitcher” figures to be a significant part of his identity, if not his defining quality. So, to wake up one morning with the world sort of shrugging in your face saying, “Well, maybe you’re not a good pitcher,” must have felt like quite a surprise, even if thousands of ballplayers before him had experienced the same thing.

2025 might not have been Kyle Harrison’s “make or break” season, but if he winds up achieving 10 years of major league service time, the seeds of that success will have been planted here.

It was a rough start. He allowed 8 earned runs in 6.2 Spring Training innings, compelling the Giants to option him to Triple-A a week before Opening Day. He made six starts for the River Cats before getting called up to replace Lou Trivino on the major league roster, but he was immediately put to work in the bullpen and made a solid contribution: 2 ER in 5 IP with 7 strikeouts to 3 walks. Justin Verlander hit the IL three weeks into May and that necessitated his elevation to the rotation where he had two promising starts (2 ER in 4 IP in Washington, 5 shutout innings of 1-hit ball in Miami), only to follow them with two starts (against the Padres and Rockies) that gave him an overall blah line (4.36 FIP in 23.2 IP) and restarted uncomfortable questions about his future.

So, the Giants traded him. They got Rafael Devers in return, so it wasn’t like he was a throw-in, but the organization had seen enough.

Boston immediately optioned him to Triple-A, which had to have stung. Red Sox beat writer Chris Cotillo chronicled his eventual return to the majors with this opening paragraph:

When the Red Sox first acquired left-hander Kyle Harrison as part of the Rafael Devers trade in mid-June and optioned him to Triple-A Worcester, director of pitching Justin Willard said he expected Harrison to stay in Worcester for just “a couple of weeks” before reaching the majors. Two weeks turned into nearly three months before Harrison, at long last, was finally recalled to join the big league team

He made three appearances for Boston in September: a 3-inning relief stint in Sacramento against the Athletics (0 runs), and then 2 starts (at the Rays, vs. Detroit). He struck out 13 in 12 innings while walking only 5. Except for that appearance against the Athletics, his fastball velocity didn’t tick up. It was basically 94 mph tops in his two starts. In that first relief appearance, 10 of his 20 fastballs were 95+. So, yeah, maybe the bullpen will be where he’s most effective, but compared to last season, he was still up about 2 mph across two organizations.

His other lingering problem has been injuries, and an ankle issue prevented him from debuting for Boston earlier than he actually did; so, the Giants did wind up trading out of an unpredictable position to a consistent one. Devers has been a Top 25 hitter in the sport for many years now and Harrison’s ceiling had grown fuzzy.

So, his ultimate utility wound up being what a good farm system needs: trade stock. No, the Giants don’t have a good farm system in general — or even historically — but this season, with Harrison in it, it was good enough to land a premiere hitter. That’s not the role a prospect imagines when he’s drafted by his team, and it’s certainly not what the organization tells him on his first day, but it’s the nature of the game, and the players who survive are the ones who can adapt to the oftentimes harsh changes that gets thrown their way.

The meaningful consolation prize here is that Kyle Harrison is still valued in the industry and has pitched his way back into people wanting to see what he does next. His fate is his own.