The Chargers had a good offensive game-plan to attack the Steelers on Sunday Night. While things didn’t start off great for Los Angeles, the Steelers let them hang around, and this gave their game-plan time to take hold.

The Steelers are a predominant Cover-3 zone defense. Have been for years. The Chargers came into Pittsburgh looking to take advantage of this, and the Steelers made few adjustments.

One great way to attack a stubborn zone-coverage team is to align wide receivers inside and generate matchups on linebackers. The Chargers did this often on Sunday night. Wide receiver Keenan Allen caught 14 passes, and 6 came against linebackers. The Steelers were content to allow this to happen.

With the game tied at 30 and 1:21 remaining in the 4th quarter, the Chargers faced a pivotal 3rd-and-4 at the Steelers 34-yard line. They were at the edge of field-goal range. At very least, a stop would give Pittsburgh a little more time to rally for a potential game-tying field goal, and they still had one timeout remaining. Check out the matchups below.

The Chargers went empty with three wide receivers to the right and a tight end and running back to the left. Notice the cornerback over the running back to Rivers’ left and the safety over the wide receiver to his right. Also notice linebacker Jon Bostic over Keenan Allen in the slot to his right. These were all indicators of zone coverage (You don’t play true man coverage with a corner on a running back and a linebacker on a wide receiver).

Since the Steelers were matching up to the routes in zone coverage (pattern-reading instead of spot-dropping), the Chargers wanted to ensure that Allen would be isolated on Bostic. So the two outside receivers ran vertical stems, taking the defenders over them downfield.

Allen was left 1-on-1 in one of the more favorable mismatches a quarterback will ever see. Rivers stood in the pocket and delivered the ball with a defender in his face.

The Steelers chose to try and win with pressure, as they often do. They brought five on this play and counted on the rush to get there in time. The idea was to force a quick throw, rally to make a quick tackle, and their unfavorable mismatches wouldn’t be quite as vulnerable. They chose wrong.

This is how the Steelers like to play on defense. They have for a long time. To some degree, you can’t argue with it. Entering Week 13, they led the league in sacks and were 3rd in sack % (percentage of pass attempts resulting in a sack).

If the rush doesn’t get there in time, though, the coverage in this type of defense really gets exposed. This is especially true against a seasoned quarterback like Philip Rivers, who isn’t afraid to stare down a pass rush if it means completing a pass.

Even before this key 3rd-down conversion, the Chargers had a good game-plan for attacking the Steelers’ Cover-3 zone concepts. Their first touchdown of the game came off a great Cover-3 beater (we know, Steelers fans, it was a false start). The Chargers used a post-wheel combination, as you can see below.

This first image shows that the cornerback in Cover-3 is responsible for the deep outer third of the field.

Here, you can see the route concept. Focus on the top two routes.

The reason this route is great at breaking down Cover-3 is that the outside receiver looks to be attacking the cornerback’s deep outside zone. He then carries that corner inside after getting enough depth to become his responsibility.

This leaves the deep-outer third open to the wheel. You can see below that the underneath defender to that side was a bit flat-footed. He recognized the wheel route coming from the slot a bit too late, and wide receiver Travis Benjamin was able to get on top of him as a result.

Watch the entire play unfold below.

Great play-calling is not just defined by calling a good play that breaks down the coverage. It is defined by using concepts that build off one another from play to play. Chargers Offensive Coordinator Ken Whisenhunt did just that.

In the fourth quarter, with the score tied at 23, Whisenhunt dialed up another post wheel combo to attack Cover-3. Below you can see the coverage and the route combination.

The Chargers basically ran the same route concept as they did on their first touchdown, just from a slightly different formation. They also incorporated motion this time. There is one key difference in this play from the previous one, though. Notice the running back. On this play, he released to the side of the post-wheel instead of away from it. This was key.

Watch it unfold below. The post took the outside corner inside again.

The wheel again worked off the post. The difference here is that the flat defender recognized the wheel and got on top of it. The Steelers were not going to get beat by the same route for a big play again!

The inside route pinned the underneath defender inside and took him upfield just a bit.

The result was a wide open flat for the running back, Justin Jackson.

That was an easy big gain for the Chargers. Really, it was a tremendous job by Whisenhunt. He put himself in the shoes of the defense – they were not going to let that post-wheel beat them again. So he added a wrinkle by overloading that side of the field with 4 pass-catchers. The Steelers had no answer.

There were a few other key variables that led to the Chargers’ thrilling victory. First, running back Justin Jackson made a difference running the ball in the second half. He showed great patience and stop-and-start ability. His 63 yards on 8 carries did not just come from gaping holes (although there were a few). He made defenders miss and found yards where there seemed to be none.

Philip Rivers also was a difference-maker. He made some great throws, but more importantly, was able to fire accurate passes with bodies around him. This has always been one of his best traits, and it came up in some important moments against Pittsburgh.

The Steelers had plenty of opportunities to win this game. But as we have seen all too often with this team, they let those opportunities slip through their hands (literally, if you go back and watch Rivers’ second touchdown pass). They continue to disappoint, and serious questions remain about the ability of their defensive scheme to keep passing games and quarterbacks possessing any level of sophistication in check.

The Chargers, on the other hand, are quietly still in play for the AFC West division title. They are one of the better all-around teams in the NFL and are 18-6 going back to last season. Whether or not they win the division, not too many teams will be happy to see them in the playoffs.