He's been the nailed-on starter for a team in the European places of La Liga for two years as a 20-21 year old, and was very much part of Barca's first team plans until their financial situation went tits up. He's also in the Brazil setup of course.
You watch his Youtube highlights and it's full of him making 40 yard recovery runs to dive in with a tackle, or barreling up the pitch on a run from deep in his own half. There are not progressive passes and dribbles in the final third, which is what he's now being asked to do.
Plus there's the general rule that it's foolish to give up on a player in their first year in England.
The question, really, is when are we going to need a proper right back again? Not at least until Conte is gone, and perhaps Paratici as well. And even at that point we'll be leaving behind a back 3-ish squad. So it's tricky.