2025 stats: 3 G (2 GS) 15 IP 1.80 ERA / 2.54 FIP, 14 K, 2 BB, 1 HR, 1.00 WHIP, 53.5 GB%, +0.4 fWAR
Trevor McDonald didn’t appear in a Giants uniform until September 16th in relief of Tristan Beck who left after 3 innings and the team up on the Diamondbacks 5-3. In the 5th inning, he gave up the lead and the Giants would lose on a walk-off to fall to 75-76. There was nothing in that appearance that prepared you for what followed.
His next appearance was five days later as a starter. Against the Dodgers. In LA. He struck out 3, walked 1 and allowed just 1 run while pitching into the 7th inning. Sure, he was chased by the cremains of Michael Conforto, who only achieved corporeal form in 2025 against the Giants, but for a quality start’s worth of time, he frustrated the Bums. Jammed ‘em up. In his next start, he struck out 10 in 7 innings allowing 3 unearned runs. The Giants ended another disappointing season, sure, but this time, they’d ended it with somebody they could add to the rotation… right?
That was certainly the refrain. Why did they waste all that time on Kai-Wei Teng and Carson Whisenhunt and openers when Trevor McDonald was right there? There’s a real answer to that question, one that threatens to put a damper on this entire review. I don’t want to do that juuuuust yet so let’s stick with the good stuff. It seems impossible that a random pitcher could outshine Bryce Eldridge’s callup, but that’s just what happened.
Heading into the season, Brady previewed the pitching staff and offered this condensed profile of a prospect the McCovey Chronicles community has been into the past couple of seems, though less excited about than others.
McDonald was finally mostly healthy in 2024, and showed just how electric he can be. A Rule 5 protection a year ago, he made his MLB debut on the final game of the season. It seems very clear that McDonald will have a quality career in the bigs … it’s just not yet clear what role it will be in.
He ended last season as the community’s #15 prospect in the Giants’ system and just the other day he ranked #12. For that, Brady wrote:
And so, McDonald — who turns 25 in February — is a tale of two arms, and you can craft whatever narrative you want around that. He’s been very unremarkable in nearly 200 innings in AAA, and the Giants have seemed extremely unimpressed […] And yet, he not only put up excellent stats in an admittedly tiny MLB sample size, but he looked the part along the way. […] he’s a groundball pitcher (53.3% rate in AAA in 2025) with a four-pitch mix … he stands to greatly benefit from a historically great catcher calling his games, and an excellent defensive infield posting behind him.
This handwringing is all because of Trevor McDonald’s fastball. It’s not fast enough. This season in the minors, he averaged 93.1 mph with a sinker (thrown 48.8% of the time) and 93.5 mph with a four-seamer (thrown 7% of the time). In September for the Giants, he ditched the four-seamer and threw a sinker at an average of 93 mph 38.7% of the time. He threw his curveball 51.4% of the time.
That’s right. Fifty-one point four percent.
J.P. Martinez must’ve said, “Hey, bro, why not flip those usage rates and setup your other pitches with your curveball?” and, that basically worked. His curveball achieved a 38.2 Whiff% and wound up being his put away pitch 32.4% of its usage.
But throwing a curveball 50+% of the time over the course of 6 months and 24 or more starts is an unstable foundation for a sturdy structure of a season, let alone a career. Landen Roupp, Framber Valdez, German Marquez and Aaron Nola all deployed theirs around 30-35% over the course of the season and that seems like the absolute limit for an effective starter.
All of this suggests that what we saw in September was a prospect getting a shot and doing great in a very small sample size, which means this review must be a little more focused on the future. Did Trevor McDonald pitch his way into the rotation? I don’t think so. We saw a great performance in a very small sample and that’s that. He would not use his curveball to that extent if he was expected to make 14+ starts. That underpowered fastball and excellent curveball would make a really nice combination in the bullpen, where the Giants (currently) need a lot of help.
But that’s not bad news, as much as I set it up to be. I, too, was singing about the fifth starter being found, but upon review, it’s pretty clear that the Giants just need him on staff, probably in the bullpen, though not necessarily. The bottom line is that after waiting his turn to get another shot, he made the most of it to such an extent that the organization now has no choice but to include him in their plans for 2026.