I think that you're all over-looking something that's rather important. Trezeguet scores a lot, right. He doesn't really help anybody else score, though. Trezguet basically either scores when he gets the ball, or gives it away. A player like Zlatan doesn't score as much, but he provides much better for his team mates. Furthermore, Zlatan can act as a target man. We have some good longball servers, but Trezeguet doesn't do anything with them. If we had a player like Zlatan who can take down highballs, but also has the skill to make something of them, then we would be a much more dangerous team. The point is that Zlatan and Trezeguet each have their own strengths and weaknesses. If you value a complete player who will contribute to the team, then Zlatan is your man. If you think that Juventus is fine playing with ten men and a wall, then Trezeguet is good.