I can see it all now: Brock makes his comeback accompanied by one of those videos the WWE does for The Undertaker.
"Back from the dead!"
(Narrated by that really manly Hollywood trailer voice)
"He wants his title back"
(Brock bursts out of some shallow grave with a tombstone saying RIP Lesnar)
"Brock Lesnar - Frank Mir. Buried Alive Match for the UFC Heavyweight Title"