WHY PATS AND BRADY SPLIT

The end didn't come because of one moment when things went bad. There wasn't a horrible argument, a fight that prompted things to be said that couldn't be taken back.

No, the end of the greatest coach-quarterback relationship in NFL history came slowly, after their bond wore down gradually over two incredible, record-setting decades. In short, their dramatically different personalities finally wore each other out.

On Tuesday, Tom Brady made that official when he announced on Instagram that his time with the Patriots had ended. And while some people close to both men claim they still share a deep admiration for each other (Bill Belichick even used the word "love" in a statement praising Brady on Tuesday), the Brady-Belichick relationship was one more of tolerance than closeness.

We all know what Belichick is. He's a cold, calculating leader. That isn't written with disdain, but as a mere fact. To him, football is a math equation:X + Y = Super Bowl. Do your job, watch film, follow the culture set by him and Brady and go win. If robots created a football franchise, it would be the Patriots.

Then there's Brady. For all of the QB's fiery personality and hardcore dedication, there also exists an extremely friendly, funny and charming person underneath the helmet. His popularity in the locker room was not merely a function of all the winning he's done—it also came because he was extremely well liked.

Everyone from stars to the last person on the roster stopped by Brady's locker. He often welcomed new faces to the team, no matter the position. He was known to even welcome new people who worked throughout the franchise, not just teammates.
 

Former Patriot Rodney Harrison once told me Brady was one of the nicest guys he'd ever met.

Belichick is a brilliant piece of artificial intelligence. Brady is a football savant with the ability to empathize.

Those two personalities often clashed, out of public view, and yet they produced staggering results. 

The duo has the most regular-season wins (219), postseason victories (30) and Super Bowls titles (six) of any coach-QB pairing in NFL history. However stunning it is that their partnership is over, there are many around the league who have long been surprised the Belichick-Brady relationship lasted this long. As productive as their relationship was, it wasn't considered a close one, and at times, felt quite distant.

That isn't all that unusual among the greats in league history. Bill Walsh and Joe Montana weren't pals. Jim Brown and coach Paul Brown didn't lunch together. There are other examples, and this is how it sometimes goes.

But it is different from Brady's relationship with owner Robert Kraft, who said he loved the Hall of Famer-to-be "like a son" in his own statement Tuesday.

In the end, that wasn't enough to convince Brady to stay. The NFL Network's Ian Rapoport reported there are big offers out to Brady from both the Chargers and Buccaneers, and both would offer very different workplaces than what Brady is accustomed to.

Chargers coach Anthony Lynn is close to his players and warm. Bruce Arians in Tampa sometimes acts like a grumpy uncle but is extremely good with players—especially quarterbacks.

No, those coaches don't have the brilliance of Belichick (no coach does), but Brady's relationship with his next head coach will be almost...unusual.

A former Patriots player offered me an illustration of the Brady-Belichick dynamic once. He said at one time he had asked Brady what was his relationship really was like with Belichick. Brady responded: "It's good."

And that was it. No qualifiers were offered. No anecdotes. Just straight and to the point.

Yes, the next chapter for each man's life will be fascinating to watch unfold, but before we do that, let's take a moment to appreciate what these two accomplished together. The run was productive, great, eternal and likely will never be matched. It was one of the most rare things American sports has ever seen.

It also wasn't warm and fuzzy. It was, you know…good.              

Mike Freeman covers the NFL for Bleacher Report. Follow him on Twitter: @mikefreemanNFL.