The one issue about going after a manager like Allegri is what you alluded to...he is more of a defensive manager. In the short-run United Fans will enjoy the stability and return to winning ways, but in the long-run they will turn on him. He wont have the team playing the "United Way." So what you will get, is not an upward trend for the long-term health of the club, but just a dead cat bounce as the club continues to slowly decline from its once greatness.