Switching to a back 4 means one of our defenders go
It makes sense to sell Bonucci. As for why he, himself would go. Well, if we told him he wouldn't be starting week in, week out he'd want go to. Not to mention Monaco want him, they'll give him plenty of money i'm sure
As for Di Marias valuation, well it's all speculation. One thing's for sure. He's going to be very unhappy trying to break into a team with CR and Bale. In other words, not gonna happen. So we'll see how much Madrid want for him