Taosman is on to something here. You get the best players on the field. I think a roving linebacker who rushes the quarterback from varying angles coupled with a three-man line makes for a devastating defense. Lots of NFL teams adopt 3-4 blitzing packages. With the talent we have at LB (5, maybe 6 players who absolutely should be on the field), I don't think it is so far-fetched to suggest that we should throw four linebackers at the offense at a time if the ends are not getting the penetration we need. Maybe the front line gets it done this year, but they were merely adequate last year.
Alan said is that the guys we have will be "fine." Maybe, maybe not. Again, they were not "fine" last year, they were mediocre. Freeman and D'Andrea on the field at various times with Carpenter, Hawk, and Shlegel seems to be a better assemblage of talent, IMO. I agree that we cannot know for sure whether Carpenter would make for a good DE, but we can know that the athleticism we possess in the second row would make for a devastating defense from the 3-4 set where the offense never knows which of the guys from middle four is going to gun for the backfield, and at which angle.