I really don't think Lindelof is as bad as a lot of posters here make out. To suggest he's not good enough for the PL and is the sort of defender you used to get for 5 mill is ridiculous, in my view. He's a solid player, a cultured defender. He's not a star and probably would be better suited to being the No 3 man than a starting XI fixture, but I don't think he's a player that represents a critical weak point in the team. He is very rarely less than adequate, and sometimes more than that. We could use an upgrade yes, but that's also about the need to take care of the things Maguire doesn't do well, so that he can play within his limitations.
It's easy to like watching Bailly better - he's got the speed, he plays with flair and distinctiveness and determination, makes dramatic tackles. But that doesn't necessarily mean he's a better player. I think A-Man's got a good point about Lindelofs preference for shutting down rather than aggressively confronting attackers. It's not fun to watch, but it can be a very effective approach. It's also in fact an approach that the United defence as a whole seems to have, apart from AWB. They tend to try to maintain shape and stay in control of the situation, which makes them look under pressure a lot, but actually generally works quite well.