Brady cheated. That's the basic point of all of this.
Even if we were to use the Ideal Gas Law defense, there were footballs that fell well below that projected range. And all it takes is for 1 ball to be tampered with in order to be considered cheating. Taking the PSI average for all of the footballs was just a way for Brady fanboys to manipulate the truth.
But the other point to all of this is that Goodell has nobody but himself to blame for all of this.
The Patriots cheated for six seasons under SpyGate and had unprecedented success for a team in the salary cap era. He could have suspended Belichick for an entire season without pay (at the very least) and gotten that suspension because there is no union for the coaches. He probably could have done a lot more to send a clear message:
Cheating will not be tolerated in the NFL. To the point where the ruling for being caught for cheating will be so penalizing that no organization and almost all players will think twice before cheating the league, again.
Goodell didn't do that. Instead, he helped cover up the issue. Remember, just before SpyGate was uncovered, the NBA was going thru their scandal with Tim Donaghy (although the FBI later stated that there was no evidence Donaghy fixed games, he just could predict outcomes based on what his fellow refs were saying to him prior to a game).
Donaghy didn't hurt the NBA's popularity and if the NFL had done the right thing SpyGate would not hurt the league's popularity either. Instead, he covered it up, gave the Patriots a slap on the wrist and told the owners, coaches and players that the Patriots didn't do anything that bad.
It reminds me a bit of the documentary The Seven Five about Michael Dowd, considered by many to be the most crooked NYPD officer in history. The 75th precinct was Dowd's district and they had cops doing crooked things. Eventually, the district adjacent to the 75th precinct (the 77th) was caught in a huge bust for breaking into drug deal houses and stealing money and drugs.
Instead of the message being sent to Dowd, it only further emboldened him to be even more crooked because he felt that the last thing the city wanted was another crooked cop bust. And Dowd was right.
Brady is Dowd. He saw that Goodell wanted nothing to do with busting the Patriots in SpyGate and found a new way to cheat (and let's throw Belichick in here as well, he only wrote the foreword for the little known book Football Physics which deal with how changing the properties of a football will change the aerodynamics). Brady cheated because he knew that Goodell wouldn't do anything.
But like Dowd, too much time had gone by and now the league were now willing to punish him for cheating.
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