Bernie's best is behind him but he's won a B&F at both Adelaide and Melbourne. Hardly a failed midfielder.
Vince is/was way too good to be thrown in with guys like Crowley.
You could certainly argue that he was a failed midfielder at Adelaide post 2009 though. He copped some injuries in the years following and wasn't able to return to his best form. Some people argued he had a poor work ethic at the Crows as well. When he wen't to Melbourne, they deshackled him and put him in a tagging role which worked out really well for them.