Kansas City waited abounding years to win their second Super Bowl. Fifty years is a very long time between victories. Considering the Chiefs are usually a very competitive team, if not a top team in the NFL, they had not advanced to the big game since they last were crowned champions. Hank Stram coached that team and Len Dawson was the quarterback leading them to an upset victory over the heavily favored Minnesota Vikings. Heck they rarely appeared in the AFC Championship game since their first Super Bowl.
When the team from the great state of Missouri does regress, it usually results in some level of change at coaching or in the front office and they are quick to return to being relevant.