Roth, like Pollack, would be better as a 3-4 OLB than a 3-4 DE... That said, a DE like Marcus Spears or Chris Canty would be a much better fit as a 3-4 DE and might be better off going to a team where they'd be used in that capacity as opposed to playing DE in a 4-3.. Spears might be asked to move inside in a 4-3 which doesn't cater to his strengths.
Roth and Pollack are better pass rushers and playmakers and would be overmatched against the run if they were to be in a 3-4 as a DE. Both are gifted players but just like any player.. coaches need to put them in positions to get the most out of them. Think Kevin Greene.