Same old question: small DEs or big OLBs
I love this debate. There are guys like Nick Perry, Vinny Curry and Mercilus who are DEs and you ask "Can they learn to drop back and cover"? Then you have guys like Ingram, Upshaw and Massaquoi who are about the same size but listed as OLBs. You ask "Can they put their hand down and be a DE in a 4 man front"?
Personally, I'd look for the guy who already has the most experience in dropping back and covering (out of the guys above). All of the above can get after the QB. Do any of these guys fit the bill?