How did Philip Rivers and co manage it? James Dudko explains...
They did it by beating man coverage schemes with bunch formations and route combinations.
The tactic worked to perfection on three of the game's biggest plays.
The first came in the opening quarter with San Diego facing 3rd-and-5 at the 50-yard line. The Chargers aligned a bunch formation of three wide receivers on the right side of their offense.
At the top of the bunch was Seyi Ajirotutu. Behind him, from left to right were rookie Keenan Allen and Vincent Brown.
At the snap, Ajirotutu broke right to the outside. As he did, Brown went inside on an underneath route to the left.
Allen attacked the gap created by this criss-crossing, on a deep slant pattern over the middle. Quarterback Philip Rivers hit him in stride and Allen completed a 29-yard gain.
That set up a field goal for San Diego's first points of the game.
One of the keys to the play was a pick by Ajirotutu on outside cornerback Marcus Cooper. The Chiefs had initially used three corners, Cooper, Brandon Flowers and Sean Smith, to cover the bunch.
They were all in man coverage. The problem with man coverage is how it reacts to a multiple route combination like the one the Chargers ran here.
In man coverage, defenders can't trade routes the way they do in zone. They have to stick to the player they are originally assigned to cover.
Cooper's responsibility was Allen, while Flowers covered Ajirotutu and Smith took Brown. So when Ajirotutu broke outside, he ran into Cooper and prevented him from coming across to trail Allen.
It is a common tactic used to counter tight single coverage. It borders on legal and gives offenses that use bunch formations and multiple routes a huge advantage.
In the fourth quarter, the Chargers used a smaller bunch on the same side for an even bigger play. On 3rd-and-2 at their own 40, they put tight ends Antonio Gates and Ladarius Green together in the slot on the right.
Prior to the snap, Green motioned inside Gates. At the snap, Gates broke outside to the right on a quick out-pattern.
Green broke the other way on a deep crossing pattern over the middle. Because of the threat Gates poses, he took double coverage with him.
That left Green matched up one-on-one against slot cornerback Flowers. The 6'6", 240-pound tight end won that physical mismatch and caught Rivers' pass in stride.
He then outran his coverage to finish a 40-yard scoring play that gave the Chargers a 34-31 lead.
Because the Chiefs played man coverage across the whole formation, they had no deep safety to help bracket Green over the middle.
They tried to rotate Qunitin Demps deep from the other side, but Green was too fast for him.
The Chiefs would soon be punished again for their heavy reliance on man coverage.
With 31 seconds left in the game, the Chargers were trailing by four, but had moved to the Kansas City 26. They put three wide receivers on the left side of their offense, but this time spread them out.
Ajirotutu lined up outside closest to the sideline. Brown and Allen were the inside receivers.
The Chiefs played strict man coverage underneath with just one deep safety, Demps, behind it. The Chargers would challenge Demps with multiple routes.
At the snap, Ajirotutu ran a post pattern to the end zone. Brown also ran vertical, attacking the inside seam. Allen went on another crossing route over the middle.
Demps now had three routes to focus on, including two inside breaks. Most defensive schemes are designed to defend the middle first, so Demps was naturally drawn to Brown and Allen's inside routes.
That meant he was late getting over to Ajirotutu when Rivers heaved a deep throw to the outside. Ajirotutu made the catch over Smith, who had no safety help from Demps, for the winning touchdown.
The Chiefs have thrived with physical, man coverage all season. But their over-reliance on the concept was exposed by the Chargers.
Although top pass-rushers Tamba Hali and Justin Houston suffered injuries, it was the way San Diego manipulated coverage that really undermined the defense that had allowed the fewest points in the NFL before Week 12.
The Chiefs must fix the problem before their rematch with Peyton Manning and the Denver Broncos in Week 13.
image: © Jeffrey Beall