I took the fam to a game a few years ago and we opted for a later flight.
The way I saw it there was no way I was gonna spend my day stressing about making a flight. What if it turned out to be a long game that came down to the last play or went to OT? No way I was going to miss that hurrying out of the stadium.
The game I went to was close well into the 4th quarter. We stayed the whole game, let most of the stadium empty before we headed out basking in the win. We had time to stop for dinner on the way to the airport and it was very cool being amongst happy Bills fans, it really capped off the weekend.
Not an apples to apples comparison with you since I'm a lot closer than Atlanta, but if you're heading to Buffalo specifically to see a Bills game I'd try to prioritize the game over the flight home.