I honestly think the regression by the offense is simply experienced coordinators getting Joe Brady on films.
They see what he does against certain defenses, so they add some new wrinkles to essentially take away the 1st option.
Shakir demands some bracketing too...without that it it was easy to wipe out the 1st read for Josh and force him to 2nd and 3rd options.
I think the big thing right now is that the lack of a downfield threat. MVS, Samuel, and Hollins to some level were supposed to be downfield threats to stretch the field. They haven't been. The only player who has consistently open in single coverage has been Coleman, and he's not a speedster.
So teams have been able to, essentially, not respect Allens deep ball threat because no one can catch it. It's the reason we saw so many shot plays early was because it was open and our guys couldn't catch the ball. We even got Kincaid in single coverage by a linebacker streaking down the field and Houston's LB made a hell of a play defending the ball
Honestly, we need to connect on a few PA deep balls to really force the teams back into two high safety to let the short game work.