I like Sanchez, and although there is hopefully some truth in saying that he will improve once he is fully up to the speed of the Prem league, I don't think he will ever be the steady reliable DM that people want.
He believes in his own talent, and is happy to take risks playing in a position that doesn't go well with risk. He plays on the edge, with a smile on his face, and as a 29 year old international he might not feel that he needs to change too much. I think he is one of those players where you will have to live with the errors. Some might not think that he is worth it, but I see a lot of positives in what he brings.
He isn't Makelele and I don't think he wants to be.