I see Evans and Helmuth are thinking about leaving the team. Yes, this hurts bottom line depth. But, the team will be alright this year.
From what I see, the returning DTs are Martin, Sagesse, Campbell, and Tim North. I'm not sure more than one will be on the field in most situations, but I doubt Helmuth would've ever been on the field even if two were needed. Plus, Van Bergen, Patterson, and Banks could provide depth if it was really needed. In all, Helmuth leaving hurts to the extent it would hurt the roster if Dominique Ware left the team. Exactly.
As for Evans, he was slated for the end slot. Seems to me that he was behind at least Brandon Herron right now, and would be behind Craig Roh by midseason. Also, don't forget Steve Watson is there too. So, there were 4 people for one position, one leaving won't be critical.
The upside here, is obvious. This gives Michigan 2 more scholarships to hand out. Come on down Mr. Talbott. Bring Mr. Fortt with you.