Clearly it isn't. Offense effects how and where and when the defense plays and the defense effects the same thing for the offense.
You know my thoughts on this. If I were to assign some type of percentage for the Toledo and USF losses it may (anecdotally) look like 60% offense and 40% defense.
The Defense is and has been bad, but I still maintain the position that if the O had taken care of business in the first halves of both of those games (at least 2, maybe 3 TDs left on the field because the offense couldn't convert in both games) then the rest of the game looks very different.
I guess the D may have gone into Prevent Mode even with that hypothetical lead and blown it as well. Why knows.
But one thing a large lead at the half does is force the losing to team to be one dimensional. They abandon the run out of necessity to keep the clock more in their favor, thus making a comeback possible.
No need to thumb down the post though, all fun discussion.