Challenge to the replace Roof crowd: Name a good college defense that doesn't have disruptive players on the DL.
Good DL disrupt your offense. If not directly, then the offense has to expend too many blockers to handle them so that the LBs run wild.
Roof got here too late to affect the first recruiting cycle. He has since brought in the likes of Adams, Henderson, Glanton, St Amour, Woods, C Martin, et al. All good looking prospects. However, unless someone's a total animal DL takes development. Vance Walker played early but wasn't really an animal until his final year. Michael Johnson not a force at GT until his senior year. Daryl Richards played but not a force as tr-fr. Derrick Morgan was pretty good even as a tr-fr but he came in as already an animal. Those guys are hard to get.
When Venables got to Clemson their D wasn't all that great his first year, even with how Clemson recruits. Then got better. Then got lights out. Their DL now eats people. VT's DL eats people. When it came down to it, Pitt's DL--while not terrific--was better than ours. Good defenses have good DL's. Our DL IMO is at best middle-of-the pack and probably below average. This year K-free, Rook, & Gamble would play for a lot of teams but probably wouldn't start for the better defenses. Kallon would be situational at best. The other kids probably wouldn't play much.....maybe Simmons rotating in to spell a DE.
All this said, there are good DC's and bad DC's. It's just really hard for me to tell which Roof is right now because of where our DL is right now. To the it-will-always-be-this-way crowd I can't say that you are wrong. IMO it will be this way until we get a better, deeper DL. Here's hoping we begin to see that in the 2nd half of the season, but IMO we are still 1-2 years away.