Pitcher Potpourri: The mid-range lefties disappear overnight

At first it was a trickle. A Gregory Soto here, one Hobby Milner there. But on Tuesday we were staring at a veritable deluge. In a single day, the short- to mid-term left-handed pitching market was plundered like a Ralph’s on the Wednesday before Thanksgiving. In quick succession, three cromulent lefties made deals. First of all, it was Caleb Thielbarreturning to the Cubs on a one-year pact. Foster Griffin followed, lured back from Japan by a $5.5 million guarantee from the Nationals. Finally, Caleb Ferguson affiliated with the Reds, also for one year. (later on Tuesday, Drew Pomeranz joined the party; he agreed to a one-year contract with the Angels, which will be covered in a separate post.) Let’s review each of these deals in the order they were signed:

Caleb Thielbar

When Thielbar showed up at one of these raids this time last year, conditions were more dire. The weathered middle reliever had just dropped a stinker, walking 11.1% of batters on his way to 47 1/3 innings of a 5.32 ERA. The Cubs handed him a “here’s your last chance” $2.75 million; as Thielbar was entering his age-38 season, another poor campaign likely would have spelled the end of a surprisingly successful career for the former 18th-rounder.

Instead, the crafty veteran innovated his way out of a hole, added a new pitch and delivered a vintage Thielbar performance. Terms of his deal have not yet been announced, but considering many relievers signed for more money than expected this offseason, Thielbar almost certainly received a healthy raise to continue earning a living.

In 2025, his strikeout rate remained a few points below his peak of 30%, but Thielbar regained his command, thanks in part to his decision to replace a good portion of his big old sweepers with a tighter, cutter-like hard slider. The slutter (sorry) was a brilliant bridge between his three other pitches, which all are relatively easy to identify by hand. By adding a pitch that he could potentially tunnel with his four-seamer, curveball and sweeper, he appears to have increased the effectiveness of his entire arsenal.

See all those yellow dots on the field diagram above? That field did not exist before this year. In 2024, Thielbar primarily targeted lefties with the sweeper, throwing it 55% of the time in same-handed matchups. A pitch with all that movement – ​​an average of 12 inches of horizontal movement – ​​is difficult for shots to land. His new slider doesn’t have that crazy break, and he was able to throw it in and around the zone much easier.

And it wasn’t just a left-hander’s pursuit. Thielbar also used the new slider as a soft contact generator against right-handed hitters, pinning them inside with respectable velo and glove side braking:

Otherwise, it was a vintage Thielbar, slinging slow, high-ride fastballs and some of the sweetest curveballs in the sport. He handled both righties and lefties, and will take on a similar role in Chicago’s bullpen, navigating mid-leverage situations, especially when that leverage context coincides with a lineup of lefties.

Foster Griffin

The last time we saw Griffin in the United States was 2022, and he was languishing in Quad-A limbo, making brief cameos with the Royals and Blue Jays before hopping on a bus back to Omaha or Buffalo. Back then, he was a fringe arm, leaning on a cutter with a motion profile that happened to resemble Thielbar’s new slider. On top of the cutter, Griffin had a dead zone four-sieve at 90 mph, a pretty standard curveball and a changeup with a quality arm-side fade.

The uninspiring stuff and varied arsenal felt more fitting for a backend starter, and starting is exactly what Griffin did with the Yomiuri Giants, where he threw excellent ball for three seasons. The final was his best for the Tokyo club. He posted the third-best FIP ​​(1.78) among NPB pitchers with at least 70 innings pitched, striking out a quarter of batters and allowing just one home run.

What has changed? For that, I’ll hand it to James Fegan, who wrote a short blurb about Griffin The board:

The addition of an 80s splitter is the profile-changing development since the last of Griffin’s eight career big league innings. The raw action won’t knock you out of your seat, but this past season it flirted with a 50% miss rate because Griffin almost never leaves it in wrong locations. His steep approach angle makes it nearly impossible to lift the pitch, allowing Griffin to allow fewer home runs (18) in more than 300 innings in Japan than he gave up in his last full season in the PCL (20) in 2019. Even if he now reaches a top speed of 90 mph, that’s still too much of a profile to project him beyond a multi-inning swingman role. But now that he can handle his splitter like a throwout to either side, it’s easier to watch Griffin cut a ball. Tyler Alexander-shaped niche at the end of a throwing staff.

The prospect team gave Griffin an FV grade of 35+, suggesting he’s unlikely to do much more than suck up innings for the Nationals. But if there’s any club in need of some innings vacuuming, it’s the Nats, who have some questions about the staff afterward. MacKenzie Goreand that’s assuming they’re holding Gore, which, who knows.

Caleb Ferguson

The second left-handed Caleb in this roundup is 10 years younger than his predecessor. Ferguson, once a touch of a chaser with shaky command, leaned hard on contact suppression in 2025, scaling back his four-seamers against same-handed hitters while upping the sinker to nearly 50% usage. Sometimes this worked great. His strikeout rate dropped by more than eight percentage points, but the heavy combination of sinkers and cutters gave Ferguson one of the lowest barrel rates and exit velocities in the league.

Chasing weak contact as a relief pitcher can be both a blessing and a curse. Attacking the zone with three fastballs keeps walks and extra base hits to a minimum. But it also means there are a lot of balls in the game, and one day the BABIP gods will take revenge and rain misery on your poor ERA. Unfortunately, this happened to Ferguson at a crucial time. After being plucked from Midwestern obscurity in Pittsburgh and into the playoffs in Seattle, he initially performed well before falling into a wave of poor performances in late August and early September. In a tight postseason race, that was the case: Ferguson didn’t get many opportunities to capitalize the rest of the season, and his brief playoff run went horribly. Ferguson was brought in to close a seven-point lead in the ninth inning of ALDS Game 3 and allowed three runs without recording an out, making Then Wilson to throw Andrés Munoz on a day when he could have secured some crucial rest. It can’t be great when a reliever gets shot at on a big stage in his final moments before hitting the open market.

For most of his Mariners tenure, Ferguson was treated like a member of the B team, used mainly in losing efforts. Will the Reds, themselves a recent play-off club, rely on him to take the lead in close games? It’s a bit on the edge. RosterResource sees Ferguson as the fourth arm out of the pen Emilio Pagan, Tony SantillanAnd Graham Ashcraft. Astute readers will notice that all three of these guys throw baseballs with their right arms, and so Ferguson will take on the mantle of Most Trusted Lefty and take that loosely held title away from him. Sam Moll’s fingertips.