sheshnu It's not even really performances that matter, just points. Performances only matter when they help you console yourself after a defeat.
I think they can give you a good idea of what the side is capable of - both highs and lows.
For example, again us, last season, what was worrying was that we seemed more up for it in the bigger games and tended to do poorly against teams around us. Given that we seemed to peg everything on beating Fulham and Bolton at home and having "three teams worse than us", this seemed a rather unhelpful attribute.