Carroll will never be a good targetman.
He doesn't have the skillset or application, and it's not something you can just learn.
Shola Ameobi is a limited footballer - but he's what I'd consider a targetman. Holds the ball up well at his feet, draws fouls when there's nobody around him, uses the ball well (and is good in the air).
Carroll is a completely different type of player and people have to realise that. Just because he's big it doesn't mean he is, or ever will be a good targetman.
IMO it is something you can learn. Ive seen it happen twice with Cole and Zamora. Zamora being the biggest candidate. Cole always had the strength but his ability with the ball at his feet used to be embarassing. Once Zola got to work with him he improved that part of his game out of sight.
Agree with the last part. ATM hes not a good targetman so why use him in that role? Thatd be like signing Nikolai Zigic and hitting balls over his head to run onto.