I'd add "several recruiting mistakes" on the top of my list. With roster sizes and scholarship limits as they are, you just can't miss. And we missed on several recruits. (I won't name names but we can all see it.)
This has the feel of a coaching staff that's just playing out the string. (playing favorites, failing to make changes or respond to opponent in-game changes, failing to deter mistakes) The only good thing of an early season end is that we get an early start on coaching staff changes. It's past time for fresh approaches and fresh thinking.