Their defense isn't performing well. They have both fullbacks and are extremely sloppy. De Gea has papered over that. So Alderweireld and Sandro will be significant improvements on their current lot.Totally agree, Sandro + Alderweireld and Hysaj are being talked about currently and they're all very good players but is the problem really the rags defence? They got 19 clean sheets and only conceded 28. I'm more than happy to see them spunk money on a defence that is already performing well. Yes they need replacements for old players etc in there but is it really going to help bridge the huge gap between us? I don't think so. They need to sort out their midfield one way or another, sign someone for the RW and address the fact that Mourinho seemingly doesn't understand how to set teams up offensively any more.