I think Rampage is a lil overrated, he's improved a lot but Silva and Shogun can still take him out. I wouldn't say Wandelei is overrated, he had a bad gameplan against Chuck and took some hard ass hits and Liddell still couldn't finish him.
As for Shogun, one loss doesn't really prove anything, I hope he recovers strong and gets his conditioning better next time, he'll be a wrecking force in the LHW.
Henderson went 5 good rounds with Jackson, and lost to a Anderson Silva at his prime best, #1 p4p fighter in the world. I would not call him overrated, he's still a top 10 contender in both MW and LHW.
Surprised you didn't mention Cro Cop or Kevin Randleman -_-