Caleb Thielbar Has Established Himself as Another Successful Cubs Bullpen Project
I wrote recently about how Brad Keller‘s improvement since joining the Cubs has him in line to be their closer, but he’s not the only reliever who has made significant strides via the pitching lab. Caleb Thielbar had a 5.32 ERA and a 1.56 WHIP with the Twins in 2024, both the worst marks of his career in a full season. While he had put up better numbers in the past, we’re still talking about a 38-year-old journeyman who spent over a decade bouncing between five MLB organizations and the then-independent St. Paul Saints.
Ed. note: If you haven’t already seen it, you really need to check out “The Saint of Second Chances,” a Netflix documentary about Mike Veeck, son of the legendarily infamous Bill Veeck. It’s a tremendous story of redemption and fatherhood, told through the lens of baseball.
This past offseason, the Cubs signed Thielbar to a one-year, $2,750,000 deal that many believed at the time was an overpay. He’s been better than anyone expected as yet another successful project for Tommy Hottovy and the pitching department, posting a 2.12 ERA and 2.65 FIP over 59 appearances so far.
Caleb Thielbar, Devastating 75mph Curveball. 🌈 pic.twitter.com/R0j8oU7M9x
— Rob Friedman (@PitchingNinja) June 6, 2025
One noticeable difference in Thielbar’s performance this year is the number of swings he’s getting out of the zone. His chase rate has gone up 5.3 percentage points from last season, although he’s actually throwing more pitches in the strike zone than he has in the past. When he’s throwing his fastball or one of three breaking balls out of the zone, it’s often on purpose to get a whiff.
His four-pitch arsenal is broader than the average reliever’s, and he uses each pitch rather often. His 76 mph curveball makes up nearly 30% of that repertoire and he has the ability to tunnel it with his 93 mph fastball, as shown in the video below.
Caleb Thielbar, 92mph Fastball (foul) and 75mph Curveball (backwards K), Overlay.
Why you might give up on that curveball. pic.twitter.com/yhNS0i5mwq
— Rob Friedman (@PitchingNinja) June 6, 2025
Velocity is a big key to being a successful reliever in today’s game, but Thielbar’s fastball sits in the 25th percentile among MLB pitchers. Instead of blowing it by hitters with pure gas, he uses it to help set up his breaking pitches and vice versa. For example, he was able to strike out Aaron Judge on a four-seam fastball that was clocked at just 94.4 mph.
Thielbar started off the at-bat with a curveball and slider, following that up with another curveball to give himself a 1-2 advantage. Although you’re never truly in the driver’s seat against a hitter as good as Judge, Thielbar blew the MVP away to send the perennial AL MVP frontrunner back to the dugout.
There are so many specific examples of Thielbar’s effectiveness, but looking at the baseline stats should be enough to convince fans that the Cubs have succeeded with yet another bullpen project. His 0.82 WHIP is tied for the fourth best among relievers, and his 6.3% walk rate puts him in the 89th percentile. He’s limiting barrels, owning a 32.8% hard-hit rate that is in the 93rd percentile, and he’s clearly not afraid of the big stage.
Oddly enough, one of Thielbar’s greatest strengths may also be the reason he’s best served in a more situational role rather than closing games regularly. The southpaw is holding left-handed hitters to a .132/.181/.250 slash line with a .189 wOBA against. Being able to deploy him late in games against tough lefty batters gives Craig Counsell an advantage that will help to set up Keller or whomever the Cubs go to at the end of games down the stretch.
