Part of the problem stems from their bookend tackles. Here's the analysis from Pro Football Focus after their win over the Seahawks:
They’re teammates on the Packers, and teammates on this list. Aaron Rodgers was running for his life as Barclay, filling in for injured right tackle Bryan Bulaga, allowed an unbelievable 10 QB hurries. Bakhtiari was hardly better, allowing seven QB hurries and both of the Seahawks’ sacks.Neither of them is particularly strong when it comes to getting a push in the run game, or holding up against a bull rush on passing downs, but that pass blocking criticism above is a little too harsh. While they did allow many QB hurries, those hurries rarely resulted in hits or sacks. Both tackles were pushed around but they stayed on their blocks, which made pursuit difficult, and Rodgers moved around to find wide open areas where he picked the defense apart, as he did on this touchdown pass:
The tackles can hold up against the pass rush better than they can open up big holes for the running backs. It also doesn't help that Lacy might miss the game as he recovers from a sprained ankle. Though RB James Starks proved that he can be effective replacement, the Chiefs defense is really good against the run.Aaron Rodgers decided to test Richard Sherman So James Jones decided to beat Sherman for six. TOUCHDOWN! #SEAvsGB http://t.co/UEB0iQ3v7w— NFL (@NFL) September 21, 2015
The Chiefs are ranked as currently having the 2nd best run defense by Pro Football Focus, and the 3rd best by Football Outsiders. But neither site had them ranked highly against the run in 2014, so these first two games might have been a sign that they played against teams (Houston and Denver) who are having trouble running the ball.
The Chiefs were pretty good to really good against the pass in 2014, depending on the site's rankings, mostly because of LB Justin Houston, who's a terror rushing the passer. But they're still missing their top cornerback for one more game, and outside of Houston, their pass rush and coverage isn't dominate. Despite Houston's presence, I don't know how they'll game plan for him, they'll probably have an easier time throwing than running against a stout run defense.