I always thought that Berbatov's performances were always very straightforward to predict after the first 5 mins of a game.
If things hadn't gone well for those first 5 mins, you could bet he'd have a stinker. If however, he'd done well, he'd be mesmerising for the rest of the game. Both he and Nani had that weird thing about them.
In my mind, it was best to hook them in the first 30 mins if it wasn't their day. (The risk, of course, being that it could have a fatal effect on their confidence - which was by no means rock solid)