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The 49ers have the best pass defense in the NFL

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It’s not because of one person, either. This defense is playing at an extremely high level as a team

Cleveland Browns v San Francisco 49ers Photo by Michael Zagaris/San Francisco 49ers/Getty Images

To make this as clean and easy to read as possible, I’m leaving out the giant box score and breaking it down into two articles where I review the offense and defense. The Monday night game threw me out of whack, but here is the data from the 49ers debacle of the Browns. We’ll start with the defense, as this unit becomes more and more impressive by the week.

EPA compared to the rest of the league

As a refresher, here is “expected points addeddefined:

The value of any individual play can be calculated as Expected Points Added (EPA), the difference in EP before and after a given play. Having EPA as a currency allows all sorts of different play results and events to be compared apples-to-apples, taking into account the fluctuating value of yards and downs as the other changes. And this allows for really interesting analysis when applied on a holistic level. For example, EPA shows that a “staying ahead of the chains” run of 4 yards on first down is most often a negative play. The rare exceptions include plays at the outer end of field goal range.

On the season, the 49ers are allowing a success rate for opposing offenses through the air of 32%. That’s 14% above league average. It’s ridiculous how efficient the Niners have been on defense. They’re not running these crazy blitzes like Baltimore, and hoping it works. They’re rushing four players, depending on them to win, and using instincts and speed on the back-end to take routes away.

For defense, you want to be in the lower-left quadrant. The 49ers -0.31 EPA per dropback is the seventh-best since 2008. EPA has its limitations, as it’s dependent on where the ball goes, but there is plenty of value in that and CPOE, which is completion percentage over expectation. That stat includes throw depth, receiver separation, and a few other metrics. I would strongly suggest you read more about it. It’s worth your time. As you can see, the 49ers are passing with flying colors in both areas.

Kitchen’s closed

The Browns had a success rate Monday night of 23%. They were only successful on 11 of their plays. Think about what Cleveland did. They ran a trick play to start the game, and few deep out routes on Richard Sherman, a trap play that went for 37-yards, sprinkle in another play here and there, and that’s it. It’s mind-blowing how much they struggled to move the ball.

The 49ers weren’t sending the house weren’t sending five and six guys every play. Robert Saleh only blitzed four times in 46 plays, but you wouldn’t know by how often the defensive line was in the backfield.

Shark week

As Brian Baldinger described the Niners front four, it was like an episode of Shark week.

That’s not limited to the defensive line, though. The Browns had their teeth kicked in at every level. Fred Warner and Kwon Alexander swallowed up routes at the second level, and, Kwon especially, played with a level of physicality that Cleveland was not ready for. Here are the stats from the defense:

Seven missed tackles, but not all missed tackles are created equal. I believe only one cost the defense. For example, Tartt’s missed tackle came when he was diving in the backfield, was able to change the running back’s course, and that allowed another player to make the tackle at the line of scrimmage.

The defense also only committed one penalty. That’s a huge win.

Nick Bosa had nine wins at halftime. After the first possession or so out of the second half, the Browns offense went on cruise control to try and get out of the game healthy, which I don’t blame them. So the opportunity for wins wasn’t there for the defense. There were enough wins in the first half by the front seven for the entire game, though. Ronald Blair continues to excel in his role, as does Arik Armstead. Dee Ford is very good; we just haven’t talked about him much. Three of those wins came on 13 pass-rushing snaps. He’s been winning an insane pace all season; he’s just been limited.

Second level

Maybe the 49ers didn’t pay Kwon Alexander enough? Both he and Fred Warner are a step ahead of the offense and have been all season. This play below is a great example by Warner.

Warner was taking away deep, intermediate routes. Alexander has taken away all the shallow routes, and that’s been a vital part of the 49ers’ success.

As I mentioned, the 49ers only blitzed four times. Warner batted a pass on one. Kwon blew up the running back on another.

Alexander is fierce, aggressive, a bit reckless, but he makes plays. They’ve been tremendous this season.

E-man, what a game

Mayfield completed eight passes all night. That alone is a victory. When you hold a QB to eight completions and 100 yards in the air, I like your odds to win. As much credit as the pass-rush deserves, the secondary was just as good.

Two failed completions for good measure.

I was stunned that the Browns didn’t keep attacking Sherman on out routes. On K’Waun William’s interception, Sherman and Tartt had some miscommunication. Sherm let the route go inside, and Tartt kept drifting in the end zone. Thankfully, it didn’t hurt them.

Speaking of Tartt, he’s one of the best safeties in the game for my money. He doesn’t have the flashy plays, but this game, especially, he is constantly disrupting what the offense wants to do. His versatility allows the 49ers defense not to play have to use exotic looks to confuse offenses. I’d put him on the line of scrimmage against the Rams.

If you didn’t know any better, you’d have no clue that was Moseley’s first start. He challenged OBJ at the line, he ran with him down the field, and Moseley trusted himself at the top of his route. Moseley was only beaten in coverage once all game, on a dig route, and Mayfield was under pressure that play, so nothing hurt. Here is what most of his coverage reps against Beckham Jr. looked like:

It may not seem like much, but there is a lot of sound technique in that route. It was 3rd & 7, and he’s playing the sticks. Sitting on a route against that receiver screams confidence, which Moseley played with a ton of Monday.

Jimmie Ward’s return to the starting lineup got off to a rocky start, as he was responsible for the first pass. After that, he looked like the good version of Ward, who is a fast, aggressive player that is a great fit for the “eraser” role.

The 49ers have the best pass defense in the NFL. It’s not because of one player, but because of 11. The secondary swarms you. The linebackers punch you in the mouth, and the defensive line is going to get after your quarterback, whether you like it or not. Sound, fast-flowing football where they bend but will cause you to break. That’s the formula for the Niners defense this season, and it’s the formula for success.