Strikeforce has done very well since the merge...
It is a tad different than Lombard fighting straight cans for years in far inferior organizations. Him fighting Trevor Prangley and DC fighting Josh Barnett is 2 very different things.
I wouldn't say their ex-champs, Overeem, Diaz and Shields, have fared very well. None of them have a winning record. Bigfoot does, but that is about to go back to even soon. Cung Le has a winning record, and if he was in his prime he might have been a real force when he came over.
The guys that came over are good fighters but none of them are exceptional or are going to be champ IMO.
edit: I think DC might be the guy though.