5. Whoever covers Stefon Diggs
The Buffalo Bills are set up similarly to the Chiefs in the sense that their best wide receiver is by far and away their best option. Granted, the Bills have better depth at WR than Kansas City, but they're also fairly dependent on one guy. Gabriel Davis, Khalil Shakir, Dalton Kincaid, and Dawson Knox are all nice players, but Diggs is by far and away the best receiver.
Whether it's L'Jarius Sneed or Trent McDuffie (perhaps a mixture of both), whoever is tasked with covering Diggs needs to have a strong game. Stefon Diggs is one of the best receivers in the NFL and is a true threat to wreck the game against a great Kansas City defense.
Another reason why covering Diggs will be important is because Steve Spagnuolo likes to blitz, which means fewer players in coverage, thus amplifying the importance of covering well. Spags also likes to blitz Sneed and McDuffie, especially the latter, so one of them is asked to rush Josh Allen, the other needs to hold up or they risk surrendering a big play.
In the 2022 meeting between Buffalo and Kansas City, Stefon Diggs burned the Chiefs' secondary for 148 yards and a touchdown. The one main difference in this game is that all of the young cornerbacks are more experienced and Trent McDuffie, who was on injured reserve at that point last year, will actually suit up. Whoever lines up across from Diggs needs to be up to the challenge.