Realisticly , how good andy carroll is going to be for liverpool?

He's only 22. You can't realistically point to one thing and say "that's how good he is going to be." That being said I don't expect him to live up to the 35 million tag. I think that when he reaches his prime, he's going to be a poor man's Didier Drogba. (But not a starving man's Didier Drogba)