So, I've seen a couple mentions of Brian Orakpo pulling a disappearing act at times.
This isn't necessarily wrong - but I don't think its a 100% accurate view of what is going on. Most of the time this season, Orakpo was double and (once in a while) triple teamed. He's not good enough to consistently beat the double-team, which is why it seemed like he disappeared. I'm not sure any of the DEs in this draft are good enough to be a strong force while double teamed like he was.
However, if you want to see what he can do against a decent tackle, check out the Oklahoma game tape. He flat out destroyed Loadholt in that game, who will likely become a decent tackle in the NFL.
Orakpo is not perfect, but he'd be a welcomed addition to the Bills D-line. He could definitely beat some tackles one-on-one with his quickness and moves, and he would cause matchup problems (having to block Schobel, Stroud, and Orakpo would present some problems).