Too many errors
Any time you have lost 11 games in a row to one opponent, you can bet that there have been some big mistakes along the way. The 17 interceptions during this losing streak were already mentioned, but here are some others:
11/15/2015: Manning throws four picks, gets replaced by Brock Osweiler.
11/27/16: In overtime, Brandon McManus misses a 62-yard field goal with 1:03 left to play. That sets up the Chiefs with great field position and Cairo Santos kicks a 34-yard field goal to win. Punting on fourth down would have likely led to a tie.
11/30/17: Broncos turn the ball over five times.
10/1/2018: On Monday Night Football and facing 3rd-and-10 from the Chiefs’ 28-yard line, Case Keenum overthrows an open Demaryius Thomas for what would have been a game-winning touchdown.
10/17/2019: Patrick Mahomes is injured early in the game but the Broncos can’t take advantage. Matt Moore comes off the bench and leads the Chiefs to victory.
12/6/2020: Drew Lock threw two interceptions in this game but the second one sealed it. Trailing by six points with just over one minute to play, Lock got the ball with a chance to be a hero but on 4th-and-5, he was picked off by Tyrann Mathieu to end a game in which the Broncos fought incredibly hard.
These are just some of the reasons the Broncos have gone six years without a victory over their hated rival. Obviously, if these things all trend in the same direction on Sunday night, the Broncos will likely be looking at a 12th straight defeat to the Chiefs.