Prior to 2016, only one quarterback in NFL history had posted a passer rating above 100 after he turned 39: Brett Favre had a rating of 107.2 with 33 touchdowns and seven interceptions for the Vikings in 2009. Warren Moon also had some success as he approached and crossed over 40, going to the Pro Bowl with Minnesota at age 39, then with the Seahawks at age 41. So through decades of professional football, we had a couple of examples of elite quarterbacks near or at 40 years old.
Now we have two seasons by Brady that rank as the two best seasons ever for an over-39 quarterback, and there's no telling when his success will fade.
Brady had a rating of 112.2 as a 39-year-old in 2016, the best ever passer rating for a player over 38. This season, he has a rating of 111.7. Since turning 39, Brady has thrown just five interceptions on 840 attempts, and there's an easy argument to be made that he should have won the MVP award for last season and that he should win it this season. And yet as good as he's been, pushing past the boundaries for what we can expect from a player at his age, we also know that history tells us that quarterbacks don't gradually decline. They plummet.
At any point, Brady's career could just be over. It's entirely plausible that one day he'll have a terrible game, the worst game we've seen from him in years, and the questions of "Is this it?" will once again arise and that is the time that it could really be over. And when it is, where will the league turn to find its next superstar? Who will be the next face of the NFL once Brady joins Peyton Manning in officially retiring?
There are a number of great candidates at quarterback, but also some young players around the league who are changing the game and dominating their opponents to a degree that makes it clear we've already started to move into the next era of the sport.