He made his bones in the NFL under Pete Carroll who owns that defense. Splits off on his own as a head coach and proceeds to put up...
2015: 14th ranked defense with 21.6 points allowed per game.
2016: 27th ranked defense with 25.4 points allowed per game.
2017: 8th ranked defense with 19.7 points allowed per game.
2018: 25th ranked defense with 26.4 points allowed per game.
2019: currently 22nd ranked defense with 25.1 points allowed per game.
Five seasons he's run that team. I think replacing a future Hall of Fame DC with a dude like him is the type of suggestion that only makes sense on fan boards.
Here's another thing to consider too... IF he does turn this defense around in year one we're looking for a DC again because he'll get a HC job very quickly. Although I seriously doubt that happens because in his defense it means we're in even worse shape on the edges for the pass rush because we lack 4-3 DEs.
If I'm McVay and I have to replace Wade... I go after a 3-4 DC. Period.