Reality #1.. Lots of deeper routes are called on any given pass play & it's quite often left up to discretion of a veteran Q as to whether he will go deeper, shorter, or a "check-down"...
So you're assumption that it's all left to the offensive coordinator as to whether to go deep is off-base...Brady may have had ... and likely so... options on that 30-yard lst qtr play...and it would have been up to Brady's confidence level as to whether he would throw deep or go shorter route receivers...
Just like a Major league pitcher, who might know he's got a baseball all cut up and easier to "junkify" would have more confidence in throwing such a junk pitch in a key situation.
The key factors anybody associated with the offense is going to consider in pelting rain conditions is the catchability of wet footballs ... and if somebody knows it's more catchable, it simply increases the confidence of the person making the play.
I'll say it again... it is a crazy statement, and unlearned, no knowledge statement, that says Brady or his coordinator would think "wow, I can throw it deep now that the ball has a pound and a half less air in it". Period. It is a dumb thought to believe that.
“and if somebody knows it’s more catchable, it simply increases the confidence of the person making the play. “
Looking at Brady’s first half pass stats, he wasn’t very confident. Most of his passes were for less than 10 yards (including run after catch yards).