To be fair, I'm convinced Howard's decline was down much more to age than to RM. It's not like Klinnsman organized the best defense in the World Cup in 2014. Howard was just otherworldly. His decline happened nearly immediately after, and that after one season playing very well under RM.
For a couple years, Howard was top three to five in the league. If Hart is even an equal to Howard in his prime, I'll be alright with it.