Players out of position is a key indicator of the problem, which is very well described by UneducatedGuess in the OP of this thread:
http://www.volnation.com/forum/tennessee-vols-football/268123-shallow-vols.html .
Losing our first string (and our second string, and even our third string at DT) means that our best players aren't playing, true. But what many don't realize is that it means our players who got the VAST majority of the reps in Spring and Fall camp, as well as throughout the season, aren't playing.
We are not only dropping in talent when we go to the bare cupboard, we're also dropping in training and experience and knowledge of the playbook.
We are decimated on defense. Folks acknowledge that, but then scratch their heads and say, "yeah, but it's more than just losing those key players."
Yeah, it is. It's losing the team synchronization that comes with all those hundreds and hundreds of reps they took together. We have some kid off the sidewalk trying to play lead tuba in our orchestra, and we're wondering why not just him, but the whole band sounds off?
UneducatedGuess did a great job explaining where we are on defense. Pity more folks here won't put down their pitchforks and learn from him.