The OL has to be better than last year. Pretty much everyone back plus Kennedy returning from injury. Even if neither Crouch or Wright start the line will improve. If either or both of them look like Trey Smith did as a freshman than there could be a large step forward. I think having an average SEC O-line next year is certainly possible.
Agree DL is a huge question mark. They'll need either instant impact from newbies or players that are already on campus and haven't produced before to start doing so just to be decent.
The schedule sets up much better this year, and I think several of the mid-tier SEC teams will take a step back (Missouri, Vandy, UK). So even if the lines struggle I could still see improvement.