Ball State's best mound prospect since Bryan Bullington went No. 1 overall in the 2002 Draft, Jameson initially joined the Cardinals as a two-way player. He saw some action in the outfield in 2018, when he ranked second among NCAA Division I freshmen in strikeouts (97 in 72 innings). He opened 2019 with six no-hit innings against a loaded Stanford lineup and quickly established himself as the top age-eligible sophomore pitcher in the 2019 Draft while finishing fifth among DI hurlers in strikeouts-per-nine (14.33). He signed with Arizona for below slot value, then opened his pro career at Class A Short Season Hillsboro.
Pound for pound, Jameson's fastball was perhaps the best in
his Draft class. Listed at 6 feet and 165 pounds, he has a lightning-quick arm that allows him to deal at 93-96 mph and tops out at 98 deep into games. The Mid-American conference pitcher of the year backs up his heat with a pair of hard breaking balls, a curveball with depth and a slider with more lateral break, and each can be a plus pitch at times.
Jameson also has a changeup, though it's a bit firm and he doesn't use it very often. Though he dominated as a full-time starter in the spring, scouts worry that he's not big enough to handle the grind of taking the mound every five days in pro ball. He's athletic and doing a much better job of throwing strikes than he did a year ago, and it's easy to imagine him reaching triple digits with his fastball in that role. It's safer to project him as a reliever in the pro ranks, though Arizona will give him every opportunity to prove he can start.