Who is Spurs second best player/performer in the finals so far? (As of end of Game 5)

Even with all the rookie mistakes and blunder made by Wemby. I still think he is the Spurs best player in the finals so far.

But who is second?

Fox, Harper, Castle, Vassell all have their moments. Both positive and negative.

But who among them you would say is Spurs second best player in the finals?