If you've spent time in a locker room you'll agree that player on player, coach on coach, or even player on coach disagreements happen. Consequences can be from firing for a coach or dismissal for a player to getting called in to the head coach's office for a hard discussion (read: a good butt chewing) to a few side by side up and downs for the fighters to late night drinks and conversation for the coaches to a game suspension.
Things happen. Rules are rules but there are only a few "do this and you're toast" transgressions when you have a group of guys who are trained to be aggressive and spend a good deal of time hitting each other.
Something happened with Banks, for sure. The cascade of whatever that was and whatever the consequences were seems to have left the team, particularly the D, out of sync. Many of us ALSO noted Hooker didn't seem very crisp and effective either during the game.
Whatever went on and whatever came of it wasn't well received by the team and they didn't move on from it. What and why? We won't know. Heupel said as much in the presser, Banks said as much on social media.
Unless someone on the team decides to go rogue and spill it and likely get booted from the team, all we know is that the team wasn't the happy-go-lucky, Hooker on the sidelines encouraging and leading, defense showing composure, offense executing at a very high level TN team we have seen.
Speculate all you want and I have, we aren't going to know what created the disaster Saturday.