Don't get me wrong I loved the kid, he 100% bought into what playing for Manchester United meant, but he was far too inconsistent(up for the big games, sometimes too much, and for the lesser games playing his own game which isn't ideal as the position requires discipline), and I think SAF persevered with him so long because he had this romantic idea that he(Rafael) and Fabio(who was by far the better youth footballer of the two)would follow the Neville bros and become United's full-back pairing for United for a decade, or more
That, and the fact we were putting a lot of effort into scouting/recruiting the best 18/19 year olds in Brazil at the time, and having the Twins regularly involved in the first team would've helped in that.