I think Brock would be one of the only HW's with a chance to beat Junior. His pure mass, strength and athleticism could cause problems if he could get JDS down. I think Brock will come back and will fight Mir for the trilogy fight.
The Old Brock defitley would have a chance against JDS. The Brock we saw after his surguries and new diet has little chance of beating JDS. It would just depend if Lesnar can get back to 100% of his old self. I am actually excited for a hopefully healthy Velaquez to get his rematch. I really think right now its JDS Velaquez and then a pretty decent gap and everybody else. The only exception is we need to see Cormier against a Mir, Big Nog, or one of the top 2. Hes the hardest guy to rank right now. Who knows maybe his wrestling would let him take JDS down. Hell who knows maybe JDS has some great BJJ we havent had to see yet.