He's no loss to them with Camavinga and Tchouameni in reserve and they've done well to flog him.
He'll bomb at United.
I just don't see how he'll succeed there - whatever the benchmark of succeeding there is. Varane basically killed off his career by joining them, money obviously playing a big factor, and Casemiro looks to be doing the same. You can talk about a 'new challenge' all you want but ultimately money talks. They've both won fucking loads so I'm sure they can stomach not winning much more at this stage of their careers, especially when you're going to be earning upwards of 20 million a year.
They surely won't finish in a top 4 spot in the league, so I think their best bet this season is trying to win the Europa League. Their short term future is still looking pretty ominous though, the likes of De Gea, Maguire, Varane, Shaw, Ronaldo etc are all going to have to be replaced soon, due to age/shitness. Beyond that you've got all your overpriced, overpaid dross like Sancho, Fernandes and so on.