Werdum, Cain and Mir are the only 3 worth a shit out of those. Carwin was awfully gun shy after coming off major surgery and a long lay off, and he was a big, lumbering ogre with 0 cardio before that. Struve? He was in his first UFC fight and that was his first fight against real competition. Cro Cop? He hasn't been any good for years. Nelson? I still can't figure out what he's done to get so much praise. He's just a decent fighter with horrible cardio. Hell, even Mir has looked like shit in all of this fights. The division is full of question marks.
Carwin's a former champion and considered a big name. Far from being a great fighter, but a big name.
Struve has shown he's a top prospect in the division.
Cro Cop despite not being half as good as he was before, was still considered a big win for JDS due to Cro Cop's past reputation.
Nelson's a tough fighter who can beat some of the top heavyweights.
Mir's probably the most overrated heavyweight in the history of MMA. JDS pretty much proved this point when he pretty dominated him in every area their fight went.
Sure the division is one of the weakest in MMA, but JDS has dominated most of the big names that their is in the division which is a lot more than many other fighters can say.
Carwin isn't a former champ. Interim titles mean jackshit.
Struve is a nice prospect, but he had no experience against real competition at the time. It looks like he's starting to put it together now.
Cro Cop hasn't really been considered that big of a win for a while. Gonzaga and Kongo took all the steam from him (many people thought Cro Cop was going to steamroll through the UFC's fragile HW division, but it was quickly shown that he wasn't the same fighter)
What top HWs can Nelson beat? He lost every time he fought one.
I keep waiting and waiting for the HW division to take off, but it still hasn't yet. The future looks promising, though.