Speaking on Sky Sports, Gary Neville said: "Sometimes now I don't get as excited as I do about the signings that come in at Manchester United because I know the'’re not a part of the strategy at the start of the summer.
"Every other club is very precise, you don't see them bouncing around from one player to another. It's Frenkie De Jong, Adrien Rabiot then it ends up being Casemiro on a phenomenal contract that's going to cost the club £160 million.
"I have to say he will do well for the club for a couple of years, Casemiro, but someone in two year's time is going to pick up a player beyond their best years for £20 million that they can't shift.
"That might be Erik ten Hag, it might be a new Man United manager, it might be new owners. So there is a large element of desperation with the signing because a five-year contract for a 30-year-old shouldn't happen."
Casemiro officially joined Man United from Real Madrid last week, putting pen to paper on a four-year contract with an option for a further season.
The Red Devils paid an initial £60 million to the La Liga giants for the 30-year-old midfielder. The Brazilian will earn a salary of £350,000-a-week at Old Trafford.
