I think with attacking players the quality is generally very obvious from the get go and you don't need to go through this whole process of agonizing over will he, won't he turn out to be good.
There are exceptions of course, late bloomers and what not but there probably aren't too many forwards who arrive at a top club at 23ish, struggle for a couple seasons and then turn it all around and become world class. Those types generally tend to rehabilitate themselves at a different (smaller) club and then perhaps get another chance at the top later down the line.
I'm hoping, like most, that it somehow just clicks and he goes on a tear but right now he's not demonstrating enough to prove that he's worth perservering with.