When Did the Patriots Dynasty End?

Let's work through it.

The Patriots won Super Bowls in the 2014, 2016 and 2018 NFL seasons. 

If you are a strict judge, going by their last title, you could make the argument that their last successful moment was winning Super Bowl LIII. 

But Brady and Belichick were still going strong in the 2019 NFL season. The Patriots went 12-4 and won the AFC East. Just because they didn't win the Super Bowl doesn't end a dynasty, as they didn't win in the 2015 and 2017 seasons also. Winning the AFC East here is crucial. This was the 11th season in a row that the Pats won the division. From 2001 to 2019, the Patriots won the division 17 out of 19 seasons. Insane. 

So we're in agreement that the Patriots dynasty was still active in the 2019 season. 

But look at what happens in 2020. 

Tom Brady leaves.

The Patriots go 7-9. 

They miss the playoffs, which is essentially unheard of during their 19-year run.

And they go from winning the AFC East every year to finishing 3rd in the division. 

Since the start of the 2020 season, the Patriots have yet to win the division or win a playoff game. 

By 2020 the Patriots dynasty was over. 

- - -

The simplest way to mark the ending would be to say in the off-season when Tom Brady went to Tampa Bay. Perhaps it's the best. 

But...

Another way of looking at it would be that a dynasty doesn't just end. The torch has to be passed. 

It just so happens in the four years since the Patriots won their last Super Bowl, one team has won multiple Super Bowls. And they did it at the end of the 2019 season, marking the start of the 2020 off-season. 

So when the Chiefs won Super Bowl LIV, the torch was passed to the new kings of the league. 

- - -

So those are really the two best answers. Either when Brady left the Patriots on March 20, 2020 or when the Chiefs won Super Bowl LIV on February 2, 2020. And yeah, they're only 6 weeks apart with no games being played in between, so we're really splitting hairs. 

- - -

Just for fun though. If we roll with the theory that Super Bowl LIV ended the Patriot dynasty...it really requires a closer look at the 2019 Week 14 game where the Chiefs went into Gillette and beat the Patriots. The two teams ended the season at 12-4 and without the playoffs arranging itself just the way it did, the outcome could have been wildly different.