Same here.
Rogers gave Fedor more trouble than anyone thought he would. Then Overeem made Rogers look like a child.
Werdum beat Fedor. Then Overeem won that bizarre contest of whatever you want to call it. Fight? Not sure that applies, but he still won.
Brock was a recent UFC HW champion whose only unavenged loss was to current HW champ Cain Velasquez. Overeem made him look like he had no business in the cage.
Sometimes it's not just the caliber of competition that sets you apart - it's how soundly you destroy competition of a slightly lower caliber. Remember Todd Duffee/Alistair Overeem? Just a couple of weeks after winning the K-1 tournament, Overeem traveled to the future and ate Todd Duffee's children in front of him.
He may or may not be able to beat JDS/Cain. But I don't agree with the notion that he's some unproven heavyweight.