I think one if the things that Pearson likely needs to change is he throws too many strikes. Merryweather had this same problem in Toronto, he threw 54.6% of his pitches in the zone as a Blue Jay and got hit hard despite his primo stuff. In addition to the repertoire changes his improvements last year involved fishing for chase way more, dropping down to 47.6% in the zone. It sucks from a watchability standpoint but results wise you do generally want relievers to nibble.
Pearson dropping the lesser of his breaking balls, changing the FB shape a bit, and piping the ball down the middle less might be enough to be that late inning arm we envision.
I'd love over the next day and a half to try and find a lefty version of this profile too. Of the Cubs' high octane relievers on the Iowa/Chicago bubble Luke Little is the only lefty and obviously he's down for the year with injury.