Foster Griffin's Curveball Turned From a Weakness Into a Weapon, and the Numbers Show It

Foster Griffin is 10-2 with a 2.77 ERA and has caught the eye of at least one of your fantasy baseball leaguemates. Should you try to beat that owner to the waiver wire, or to coax him from his present owner, before the second half begins? First, let’s properly introduce him.

Foster Griffin is a 30-year-old lefty who threw a grand total of eight career big-league innings before he left for Japan, where he spent three years quietly rebuilding his entire arsenal for the Yomiuri Giants. The Nationals signed him for one year and $5.5 million in December, hoping for a fifth starter who could soak up innings. Instead they got a league-leading 19 starts, 110.1 innings, a 2.77 ERA that ranks ninth in the National League, and 10 wins before the All-Star break. Washington is 48-46 and hanging around a Wild-Card spot nobody projected them to sniff. Griffin is a meaningful reason why.

Remember, this is a guy who posted an 8.33 ERA in his last MLB look back in 2022, six-plus innings, done, no team particularly sad to see him go. Nobody was calling that a foundation to build on. He went and built on it anyway, just somewhere nobody was watching.

It's Not the Curveball

Griffin throws seven pitches: a cutter, four-seamer, sweeper, sinker, changeup, curveball, and a re-tooled splitter, and the curveball is the least of what's working. The cutter carries a plus run value that only three other lefties in baseball can match. The sinker sits in similarly rare company. The sweeper, which he only added this year, is generating a 35.5 percent whiff rate. And the splitter might be the best-kept secret in the arsenal: third-highest vertical drop of any splitter in the majors, with spin characteristics closer to Roki Sasaki's than anything you'd expect from a reclamation project.

The story here isn't one pitch getting fixed. It's a 30-year-old who spent three years in Japan building a genuinely deep, genuinely unpredictable mix, and it's working against both sides of the plate. Literally, in his case. Outside of the changeup, he throws every one of those seven pitches to righties and lefties alike, which is why there's no obvious platoon hole to exploit and no lineup script that solves him twice in the same game.

The Form Is Real

The form isn't a spring fluke that's fading either. Over his last seven starts, Griffin has thrown 43.1 innings with a 1.25 ERA and 44 strikeouts. That's not a hot week. That's basically half a second half's worth of dominance already banked. My hesitation in recommending Foster is that his 2.77 ERA is accompanied by a 4.04 FIP. His strand rate is 84 percent and should come down. His BABIP is .241 and will almost certainly climb, and significantly. My guess is the league hasn’t seen enough of him yet and will spend the second half normalizing its performance versus Griffin. He strikes out just under nine hitters per nine innings, so I’d expect a 3.80-ish ERA and more runs crossing the plate through October. Still a good arm to roster, as long as you have realistic expectations.

The Second-Half Wild-Card

Here's the wrinkle that actually makes this a second-half story instead of just a name to grab and forget: Washington hasn't decided what to do with him. He's a pending free agent on a one-year deal, which makes him one of the most attractive trade chips in baseball for a team that might talk itself into selling even while sitting at .500 with a playoff shot alive. ESPN put his odds of being moved before the August 3 deadline north of 50 percent. The Cubs, Brewers, and Pirates have all been floated as fits. That's the actual risk here, not that the stuff stops working, but that he lands somewhere his workload gets managed differently, or worse, gets shifted toward relief innings in a playoff push. Keep an eye on the landing spot once it happens. Everything else about him says add now and figure out the destination later.

The Read

This isn't a total unknown anymore, so drop the idea that you're the only one who's noticed him. But he's not fully priced in either, not with an ERA that's top 10 in his own league and a rostered rate still sitting well under half as of the last check. Grab him in shallower formats today. In deeper ones, watch the wire, because if he's still there, someone in your league is asleep at the wheel.

Questions About Foster Griffin, Answered

Is Foster Griffin widely available in fantasy baseball?
Less than you'd think given his performance, but not fully rostered either. He was in roughly 41 percent of leagues as of the most recent confirmed snapshot, and that number has likely climbed since, so check your specific league rather than assume either way.

What's actually driving Foster Griffin's breakout?
His breakout is being driven by a rebuilt seven-pitch arsenal rather than his curveball alone. His cutter and sinker both carry plus run values, while a re-tooled splitter with outstanding drop and spin characteristics has become another key weapon after his three years pitching in Japan.

Is Foster Griffin's recent stretch a hot streak or a real level?
It looks like a legitimate run of sustained performance. Over his last seven starts, Griffin has thrown 43.1 innings with a 1.25 ERA and 44 strikeouts, providing a much larger sample than a couple of fortunate outings while still leaving room for some statistical regression.

Should I worry about Foster Griffin getting traded?
A trade is a realistic possibility because he's on a one-year deal and has been mentioned as a potential deadline target. The greater concern is whether a new club changes his workload or role, making his eventual landing spot worth monitoring after adding him.