Worth noting that Jarvis is already 22 and turns 23 in December, so he's older than I would've guessed.
Fangraphs on Jarvis: "In 2019, he was 88-92 with an average breaker, above changeup, some feel. Velo climbed into 93-94 area without sacrificing plus command. Chance for plus changeup and breaking ball that plays above raw grade because of how well it's located."
Pipeline on Jarvis: "A year ago, Jarvis was a strike-thrower with a good changeup and big league pedigree (son of former pitcher Kevin), who could have gone toward the end of the top 10 rounds if he were signable as a sophomore-eligible. He wasn't and turned down the Yankees as a 37th-rounder, then opened eyes with a much stronger body and stuff in the fall. Scouts wanted to see if he could maintain them over a full college season and never got the chance to find out, but he did throw one perfect game and flirt with another in his four starts -- which may be enough for him to join Marcus Stroman as the only first-round picks ever out of Duke.
After working with an 88-93 mph fastball at the beginning of 2019 and dipping to 86-91 by season's end, Jarvis added 20 pounds to his 6-foot-2 frame and operated at 92-96 with effective downhill plane last fall and this spring. His breaking ball used to be average at best, and now he flashes a plus curveball in the upper 70s that he can manipulate into a distinct and equally effective slider in the mid-80s. His fading changeup remains his best secondary offering, grading as well above average at its best.
Jarvis has improved his control along with his stuff, posting a 40-2 K-BB ratio in 27 innings while showing the ability to move his pitches around the strike zone. He repeats his delivery well and long has drawn praise for his competitiveness. Though he's already 22, has a narrow frame and lacks a long track record of displaying first-round stuff, he couldn't have been much more spectacular this spring."