Peterson is a very good running back, but he also benefits from a very good OL
When Steve Hutchinson went from Seattle to Minnesota, Shaun Alexander went from MVP to an average RB.
Peterson also fumbles a lot and doesn’t score a lot of TD’s and he isn’t a proficient pass receiver or backfield blocker.
Peterson is not yet a complete RB
Holmgren never forgave the Seahawks front office for allowing Hutchinson to escape. It’s a major reason he’s leaving Seattle.