I need to push back on this. Where Brady ranked in various categories:Plus, it's all about the story. Brady wasn't really all that great in 2017, but he was coming off the 2016 suspension, had just won the title, got the #1 seed again and had the best QB stats.
Now 5 years later, it's a great story again - 44 year old guy having the best season, completely unprecedented.
Yards: #1
Completions: #2 (Brees)
Attempts: #1
% intercepted: #3 (Tyrod Taylor and Alex Smith)
Yards/attempt: #4
Adjusted y/a: #3
Passer rating: #3 (Smith, Brees)
QBR (whatever that means): #3 (Wentz, Keenum, both of whom threw 25% fewer passes than Brady)
AV: #1
So, by all metrics, he had a great season as a QB when compared to the competition. An argument could have been made for Drew Brees perhaps, but the two were basically neck-and-neck, and Brady's 13 wins is given credit.
Also, the top RB's, Kareem Hunt, Todd Gurley, Le'Veon Bell, and LeSean McCoy, were all pretty close. No clear dominant winner among them. Among WR's, an argument could have been made for Antonio Brown's 1500 yards. But it's not like he was clearly more impactful than Brady.