The offensive line play hasn't been terrible of late. That has been a weak spot on the team since 2006 and Lovie, the coaching staff and the front office don't seem to have a clue how to fix it. Even at it's best over the last six years, the offensive line has been inconsistent.
And the times when Cutler has been inept, it has been mainly due to shitty line play. When they protect him, he's a good quarterback.