My issue is that Valencia does not make any more errors than any other decent full-back... in fact, I think he probably makes less than most The problem is, a lot of fans seem to think that a defender should never make an error which is completely unrealistic and unfortunately for Valencia, if he makes one then it's because 'he's not a proper full-back' or he can't defend because he used to be a winger. The analysis is lazy and his errors are not frequent.
Also, what is Valencia's natural position by the way? I keep hearing he's not a natural full-back. Is he a natural winger then? He never grew up playing on the wing. He played centre midfield or striker as a young player in Ecuador before coming to Europe and being converted into a right winger... and the nature of what you might consider a natural full-back is very different to what it might have been 20 years ago. Now there is a lot more emphasis on the attacking side of the game.