Misinformed take. The list is pretty significant for pitchers who did well under Walker and ended up making money on contracts because of it.
J.A. Happ, Marco Estrada, Ross Stripling, Marcus Stroman, Aaron Sanchez, Stephen Matz, Robbie Ray, Joe Biagini, Brett Cecil, Liam Hendriks, Roberto Osuna, Ryan Tepera, even Manoah's breakout year before the arm issues are attributed to Pete Walker.