There absolutely was active litigation in 2015 (when Florio says Pash destroyed evidence) -- Brady wasn't suspended until 2016 as the case finally ended during the summer of 2016 when Brady chose not to appeal the Second Circuit's decision.
And I know it is highly unpopular around here, but I totally believe Jastremski and the other guy had hatched some scheme. Their excuses about their text messages are not credible at all.
I'm basically on the same tack you are:
* NE submits the balls at the lowest allowable pressure of 12.5psi.
* The refs do whatever they do with the ball. As we know from the texts the refs sometimes pump them up.
* Jastremski & co check the balls when the refs are done.
* Possible option A: if the refs have inflated them to over 13.5, Jastremski brings them down to 13.5.
* Possible option B: if the refs inflated them at all (i.e. they are anything over the 12.5 NE submitted them at) Jastremski deflates them down to 12.5.
* And finally, no changes were made to the balls in the AFCCG -- the NFL's own bought & paid for numbers from their "second-hand smoke is fine!" consultants prove the balls were right in line with science within the margin of error of the gauges the refs used. Presumably NE submitted at 12.5 and the refs left them alone that night.