Not sure how you can come to that conclusion pmxc.
For me:
Toews
Niemi
Buff
Sharp
Kane
Without looking at stats or anything. Really, after Toews and Niemi, you can really pick anyone to fill out the rest of that list as every single Hawk has contributed. Hossa probably deserves to be in there somewhere, I'd pick Seabrook over Keith, Bolly has done well, Hjalmarsson has only had one bad game the entire playoffs, hell even Sopel and Versteeg (two of the biggest scapegoats) have played pretty well.
I think Toews will take it. Niemi has had a decent final but far from where he played the previous 3 series, luckily the Hawks offense has been up to the task.
Buff has a case, we would NOT be here without him, no doubt. But IMO the impact made by Niemi and Toews is just slightly above his impact.