It seems as if Valencia can do everything else correctly, but his final ball is always going to be poor. Against Norwich, his crossing was poor. His final ball has been no good for the past few matches most of the time. He also had trouble beating his man, and his marker often gets the block in.
Other than that, he's done everything else well. He supports the full back very well. His passing choices are very good when they're available. He links up well with players. His movement's good when given the freedom. His only problem is the final ball, and as a winger, his final ball is the most important part of his game.
If he can't get his final ball sorted, then all of the good work he does beforehand will be all for nought. I just hope he improves it, though, so that he can get back to being the threatening player he was for our first few seasons.