WRs don't matter that much. he will start on the pitch as a CF but just make a few extra runs in behind which will actually make your attack a lot more unpredictable, he will still primarily be playing as a CF. If you have ever used Robben at RM you would know that he does get forward a lot but still primarily plays as a RM and not RW it'll be the same for Aguero as a CF.
Plus if you really want him to stay as a CF and not get in behind at all just set it to stay central+target man.
Never use a worse player for something silly like WRs that make a minimal difference IG.
I've never agreed with pure playmakers as a CF. I think they have to be a mix of both (i.e. good enough to be a playmaker or a striker) as the position is a hybrid of a striker and a CAM.
Aguero seems perfect, I just wonder whether he'll neglect his playmaking duties by never dropping deep to collect the ball, unless I set fifa 15 coins him to Target Man maybe?