I don't agree with your last line, but you're right on your overall point. Last night looked like the problem was preparation and play calling and game plan as much as it was execution by players. It seemed from afar that Heupel decided to rely on his defense and try not to turn the ball over. That's a bad game plan on the road in the SEC. You have to attack.
I don't know that coaches told squirrel to be extra conservative on fielding that punt, but even if they didn't, it's a perfect example of how coaches play calling and attitude can infect the players. If the coaches had been aggressive and attacking all night, I bet squirrel would have had a more aggressive and attacking attitude and gone after that punt. Instead, coaches were being ultra conservative on offense, and squirrel followed suit when fielding that punt. You can't expect players to have a mindset opposite of coaches.
And I guarantee you they don't practice being conservative all week on offense, so now you're calling the game differently from how you practice, which can lead to bad execution by players.