I see that we agree on certain things about Rojo's defending as a central defender. However, I disagree that he has fundamental defensive flaws or poor positioning. His positioning, awareness, and reading of the game is very good as a central defender, but we don't see that often when he's a left back as he seems to play that role more like a wing back than a proper defensive full back. Yes, he's aerially weak, but I put that down to him adjusting to the league in the first season. Surely, he hasn't faced that many aerial challenges in Portugal as he's faced here, particularly as he's often played as an attacking left back during his younger years as well. His mistakes due to wilting under pressure as well as sloppiness on the ball are two things that I believe he can grow out of if, and only if, he plays more often as a central defender. If he keeps switching between left back and centre back, then he won't cut out those mistakes or sloppy passes.