3. Win on early on downs on both sides of the ball
One can argue that winning on first down is important in every game, but it's especially true in this one. The Chiefs have to stay away from 2nd/3rd and long on offense and avoid 2nd/3rd and short on defense.
The reason this is important is because it will limit Andy Reid and Steve Spagnuolo's ability to be creative. If due to a failed early down play or a penalty, the Chiefs are in a 2nd or 3rd long situation, that will limit what Andy Reid is able to call and will make it easier for Sean McDermott to dial up a drive-killing call against a not-so-potent Kansas City offense.
On defense, allowing the Bills to run well on 1st down and set up 2nd-and-short situations will hinder how much Steve Spagnuolo can blitz and call aggressive coverages. It would also increase the likelihood of offensive coordinator Joe Brady calling a shot play, which is always dangerous with Josh Allen at quarterback. Also, losing on early downs will make it less likely that Buffalo will punt in key areas and opt to go for it on 4th down instead.
Winning on early downs on both sides will involve running the ball well with Isiah Pacheco and stopping Buffalo's running attack with James Cook. Both teams have struggled to stop the run, but the Bills saw the return of DaQuan Jones last Monday, by far their best interior run defender, and the Chiefs have proven that they can stop dangerous rushing offenses in past playoff games, such as the Titans and 49ers four years ago.
If the Chiefs can force the Bills into many 2nd or 3rd-and-long situations as well as avoid it themselves, the odds of winning this matchup will improve significantly. The strength of the offense, other than Patrick Mahomes, is the interior of the offensive line (Joe Thuney, Creed Humphrey, and Trey Smith) and Andy Reid would be wise to lean on the unit for much of this game.