Here was his scouting report, back in 2015, when he was with the Yankees:
Scouting grades: Fastball: 60 | Slider: 65 | Changeup: 45 | Control: 45 | Overall: 50
The Yankees didn't have a first-round pick in 2014, but they may have gotten a first-round talent with their top choice (second round, 55th overall). Lindgren helped pitch Mississippi State to the College World Series as a starter in 2013, then became one of college baseball's most dominant relievers last spring. He reached Yankee Stadium 11 months after signing, though his first full pro season got put on hold when he had surgery to remove a bone spur from his elbow in June.
Lindgren's stuff jumped when he started working in shorter stints. His fastball improved from 87-91 mph to 91-95, and his slider became a legitimate knockout pitch at 82-84 mph with late bite. When hitters manage to make contact against him they have difficulty keeping the ball off the ground, which is why he surrendered just two extra-base hits between college and pro ball last year.
Lindgren's sinking changeup gives him a decent third pitch that he doesn't need much now that he's not a starter. His control wavers at times, but once he shows he can throw strikes consistently, he could become the Yankees' closer of the future.
He was a strike out machine, in his Jr. year at Mississippi State, striking out 100 batters in 55 innings. His Minor League totals were just as good, with 48 strike outs, in just 24 innings. Two TJ surgeries and a bone spur in his left elbow, for which he had surgery, are a lot, from which to come back. However if he's healthy, he could be a useful LH bullpen arm. I'll be rooting for him.