Agreed Mahomes choked, but it's pretty arrogant to consider this to be the biggest upset since 2001. The Bengals are a great football team, despite having one of the worst OLs in the game.
I'm strictly talking AFC title games.
I had to go back.
But...
01: Patriots beat 10 point favorite Steelers. Keep in mind Kordell Stewart was the Steelers QB.
02: Favored Raiders beat Titans
03: Favored Patriots beat Colts
04: Favored Patriots beat Steelers
05: Favored Steelers beat Denver
06: Favored Colts beat Patriots
07: Favored Patriots beat Chargers
08: Favored Steelers beat Ravens
09: Favored Colts beat Jets
10: Favored Steelers beat Jets
11: Favored Patriots beat Ravens
12: Patriots were favored. Not by much though. Not an upset Baltimore won.
13: Favored Denver beats NE
14: Favored Patriots destroy Colts
15: Pick em game. Denver beats NE
16: Favored Patriots destroy Steelers
17: Favored Patriots beat Jags
18: Chiefs favorites. But it wasn't an upset NE won. Many pundits were split.
19: Favored Chiefs destroy Titans
20: Favored Chiefs destroy Bills
21: Favored Chiefs collapse in loss to Titans.