If memory serves, the Pats didn’t show the defense they used in the Super Bowl until the Super Bowl.
That’s because that D was specifically concocted to handle the Rams. It’s a case of give BB 2 weeks to game plan, and you will get something you have not seen before that was specifically crafted to beat the other team.
Same thing happened in the last Rams/Patz superbowl. What the Martz Rams got was nothing like what they expected.
So that’s not really a case of BB holding anything back during the season. He was just inventing something new. If they had played a different team in the superbowl with different strengths and weaknesses, we would have seen an entirely different defense from BB.
BTW it was the same with the Rams D. They did not play their regular D and instead relied heavily on subpackages to constantly disrupt what the Patz were doing.
In terms of the Rams, I like the idea that an offense is so adapatable that it can morph with the season.