If a deal is already agreed for Maguire or Alderweireld then this could make sense. Especially as the Mendes link to Wolves is so strong. It would leave us with Bailly, Lindelof, Jones and Harry/Toby as our CB options (plus Axel and Tofu). Probably the best set we could hope for for the coming season. Smalling is a solid defender, and isn't as injury prone as the others, but he looks like a drunken Bambi on ice whenever he gets the ball. I've never seen someone have to turn their entire body around the ball to make a sideways pass before. Not even at amateur level.
Rojo is definitely surplus to requirements. He's fecking rubbish. But I'd only sell Smalling if he's replaced by Harry or Toby. Definitely not if his replacement is Yerry fecking Mina. As for the whole Jones vs Smalling debate. Jones is clearly the better player by a considerable distance, but has a horrific injury record. I'd rather keep Jones, as long as we aren't relying on him to be a starter. He's good enough, just not reliable enough. Smalling on the other hand, really isn't good enough to be a starter for Manchester United. He's squad filler.