I don't like Brock, but I still think he would handle Mir in a rematch. Tim Sylvia would get taken down and mauled, and Arlovski showed a weak ground game against Roy Nelson...Brock would wrestle him down and grind him into a sticky red paste.
On the other side of the equation, I think Nog and Barnett are perfectly capable of submitting Brock. Fedor would eradicate Brock in the first round.
rickson gracie his bjj is better than mir's