Brock, like all wrestlers, need to train on submission defence, ALOT!
Mir was telegraphing his intentions and Brock stood there and tried to punch him out.
The days of one dimensional fighters are over. Brock is strong as hell but needs to train judo/jujitsu for 5 years to be in the game. Sadly, he's 30, so there's no point.
He's a good match up for purely strikers to test their sprawl and his power.
Against anyone with skill, it's over.