If Mustipher returns I don't believe DL is that great of a concern. the other DT's (especially Ellis and Izzard) got a good bit of additional experience and in game development that they would not have gotten if Mustipher had not gotten hurt. And the DT roster is pretty deep (Vanover, Brevard, Van Den Burg, Beamon, Darkwa), at least before any Portal exits.
And at DE, if Luketa returns there is plenty of depth, but not a lot of proven pass rushing. Tarburton, Vilbert, Fisher, and reports that Townley is developing along with McGraw and Mostella. Luketa would likely improve his pass rush with another year at DE, really his first full year focusing on DE. And I believe it's a safe bet that DDI make an impact as a true freshman.
LB on the other hand, has limited options and we'll need Diaz to work some magic with Elsdon, King, Katshir (if he returns) and Buddin to compliment Jacobs. LB is where I see Franklin and Diaz going hard after a transfer, even if it's not a splash player but just a good LB that can compete and rotate in.