Michael Hughes of the Northfield News has written several good articles on Caleb Thielbar over the past few years. As Parker notes above, he spent a lot of time with Driveline and using Rapsodo to break down and improve his pitches. He's definitely used technology to his advantage, both for his fastball and his curve. Here's a clip from a Hughes' article from last July:
While it’s true Thielbar has been throwing harder the last two seasons, it’s not as simple as waking up one morning with a couple extra ticks of velocity on his fastball.
Prior to the 2017 season, Thielbar was recommended by a friend to the philosophies of Driveline Baseball, a baseball training facility based out of Seattle. The facility’s website boils down its ethos simply to, “identifying what’s holding you back and developing a plan to fix it.”
Initially, Thielbar enrolled in the online program, which he described as the “basic” version of the services Driveline typically offers. Still, it helped add velocity to Thielbar’s fastball and livened his secondary pitches in the months leading up to spring training.
Once he arrived in Florida, however, the improvements and alterations fell apart, leading to the Marlins releasing him at the end of March. Knowing that Driveline’s “basic” program yielded results, Thielbar knew he needed to fully invest in the program if he wanted another opportunity.
“I’m just going to go out there for a couple weeks and learn what I need to learn,” he thought at the time.
After that first trip, he returned for his third stint with the St. Paul Saints and posted a 2.01 ERA in 22 1/3 innings, which led to a minor-league contract offer with the Tigers. Thielbar has since visited Driveline every winter.
“The technology side of the game, I’ve been able to see how all my pitches spin and I’ve been able to adjust a little bit to make them even better,” he said. “It’s just a combination of everything, really, that’s put it all together. I’m not all the way to where I want to be yet, but I’m not sure if I’ll ever be able to get there just because of some limitations with my body, but I’m trying.”"