Not an avid Valencia watcher, but so far all I've seen from him doesn't strike me as special or Manchester United level. He'll be 21 in January, and I think he lacks in first touch (to Spanish standards I mean, he doesn't hold a candle to guys like Mata or Silva that I've seen brought up here) and if being 21 he's still green at first touch coming from the Spanish youth system, he probably won't improve much. He also seems to let the ball run a little further than optimal in conduction, it would be fine if he was quicker or stronger, but that means the moment you put some weight from muscle on him he becomes a clunkier player and probably loses some of that "shining" he does have in his game. I don't want to sound harsh but with his level at his age I don't think he'll break into the European elite /top 8 UCL teams, and that's what United should be striving for. At his age, you could see some quirks and polished traits in all the other typical Spanish midfielder maestros like Xavi, Iniesta, Silva, Thiago, Mata or even Fabregas and Arteta. He feels halfway there compared to those guys at similar age, kind of a Andre Gomes situation (well, probably not that bad). If United really desire one of Valencia's best pieces this season, Guedes seems a way better player and has that special aura while being only two months older.