Not saying brock would've won the fight BUT
Cain did land an illegal looking punch to the back of the head that knocked Lesnar down that final time.
Brock slipped which set u that final barrage of punches
Brock made the same mistake that he did in the Frank Mir fight. he came out too wild and aggressive, got sloppy and got pummeled. He should've took his time.
When got the takedown on Cain, Cain was able to get back up cause Brock rushed trying to pass guard which allowed Cain to escape.
Brock should've took his time, laid on Cain, did some work inside the guard, and patiently tried to transition but he didnt.