Chiefs fan here. The defense was horrific the first 6-7 games of the season. Two crazy stats that stuck out through that span… they were allowing 7.1 yards per play (the undefeated 2007 Patriots offense averaged 6.8 ypp!) and allowed 3.3 points per possession. They were historically bad.
Now, for the question you asked, there were a few factors. First, they were banged up with a few key starters out (Clark, Gay, etc.). Frank Clark’s absence forced them to move Chris Jones to edge and the interior line suffered as a result. You could run 5+ yards down the middle of the defense any time you wanted to. As players returned, so did their scheme.
Secondly, there were a lot of dumb mistakes and penalties early in the season. So as much as injuries were to blame, so was execution. I truly believe that if Spags (DC) didn’t get it figured out soon then he could be fired this year. He did and the team quickly became one of the better defenses in the league.
Lastly, don’t discount the Melvin Ingram trade. He brought a lot of experience to a position of need and injected some much needed energy. When the team sleptwalk last week in Denver, he made the play of the game, blowing up Gordon, forcing the fumble, which paved the way for the game winning scoop and score.
This next game is the true test. Buffalo manhandled the Chiefs in Arrowhead earlier this season. Now that was the historically bad defense KC team, but looking at what Buffalo did Saturday night, both teams are firing on all cylinders right now. I fully expect Sunday’s winner to not only play in the Super Bowl, but likely be favored. Should be a fun one!