Thornton had a 4.42 ERA in AAA with a 8.8 K rate and decent numbers. BA named Thornton as the pitcher with the best control in the PCL this year.
Scouting report from 2080 ball from the AFL: Three solid pitches, but lacks CH for rotation or true out pitch for leverage relief role. Fits as a low-leverage longman able to go multiple innings.
From MLB Pipeline: Thornton has added a couple ticks of velocity to his fastball in 2018, working at 93-95 mph and topping out at 97 with riding action. He has an interesting array of secondary pitches, including a curveball with some power and depth and an improved slider that he can turn into a true cutter. He needs to refine and trust his changeup more to find success against left-handers, however. Thornton has a funky delivery but it gives him deception and doesn't prevent him from filling the strike zone. With solid stuff and strike-throwing ability, he has the ingredients to become at least a No. 4 starter. But he often gets hit harder than he should, so his long-term role may be as a multi-inning reliever.
Infield depth traded for pitching. Expect more of this type of trade. Thornton does have to go on the 40 man roster so this trade doesn't help that issue.