Per Baseball-Reference, pitchers with 35-plus K & sub-1.50 ERA in first 4 games of their franchise debuts: Pedro Martinez (1998 Red Sox), Randy Johnson (1998 Astros), Rich Harden (2008 Cubs), Chris Sale (2017 Red Sox), Gerrit Cole (2018 Astros), Joe Musgrove (2021 Padres).
First image: Mitch Keller's fastball release points in 2020.
Second image: Mitch Keller's fastball release points in his past two starts.
He said it was something he was working on in spring. Looks like it's been cleaned up a good bit.