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49ers defense vs. Saints offense by the numbers: Finding ways to contain Kamara

A statistical breakdown previewing where the Saints and 49ers biggest strengths are on this side of the ball

New Orleans Saints v San Francisco 49ers Photo by Brian Bahr/Getty Images

We know that the 49ers are slight underdogs against the Saints. Now let’s dig into some numbers to see how each team stacks up against each other. We’ll start with when New Orleans has the ball. I don’t like looking at season numbers at this point in the year. So I’ll be using data based on Week 8 and on, which was the trade deadline. It’s all about trends.

When New Orleans has the ball

Solving the run issues

The 49ers run defense has trended the wrong way. Since Week 8, San Francisco is 29th in rushing success rate. Here is why trends are important, though. On the season, the Saints have been a top-five rushing offense with Alvin Kamara. Since the trade deadline, New Orleans has only had 13 runs go longer than ten yards. For comparison, the 49ers have had 18, and all we heard for a month was, “what happened to San Francisco’s running game.”

There’s one team in the NFL that can string together long drives against the Niners, and the team played them in Week 13. It helps when you have a running quarterback and use all four downs New Orleans doesn’t do that. The Saints are the fifth-worst team in fourth-down conversions per game, so things should be “back to normal” for San Francisco’s defense.

For the season, New Orleans has had the best offensive line in football. On average, they’re creating five yards for running backs before the ball carriers are even touched. The loss of D.J. Jones could be significant if he can’t go, considering where the Saints are best at running the ball. The first table is their success rate by direction:

Now let’s look at the yards per carry by direction:

The challenge will be stopping the Saints running game up the middle. Let’s flip sides and see how the 49ers defense has done since Week 8 on the ground, starting with success rate by direction:

League average is right around 45%. There is no way to sugarcoat this. The Niners run defense has not been good the past couple of months. Here is a look at the yards per carry by direction:

Context is key here, and this is the issue when you rely on stats. On the season, the 49ers are the best team in the league at getting stops on third or fourth down when there is two yards or less to go. So while Baltimore converted a few quarterback runs, the Niners have been terrific all year. Opposing offenses have converted 44% of the time in these short-yardage situations. The next closes team is at 50%. That’s a pretty substantial gap. Jones was limited in practice Wednesday, which is a good sign for the Niners and their short-yardage run defense.

The other area of concern would be getting Kamara to the ground. He has otherworldly balance that allows him to bounce off defenders and stay on his feet. Kamara is breaking a tackle on 26% of his touches. That’s the eighth-highest in the league for players that have at least 50 touches. First place? George Kittle. Expect to see a bunch of underneath throws like swing passes and screens to Kamara to slow down the 49ers pass rush.

Open-field tackling has been one of the hallmarks of the 49ers defense. Azeez Al-Shaair missed three tackles against the Ravens, but that was such an odd game as far as what he and the other two linebackers were asked to do that I’m willing to give him a pass for tackling. One thing that has stood as is their aggressiveness. I was talking with Scott Geelan about the linebacker position, and we both feel like the team has three high-quality linebackers moving forward, and that’s not counting Kwon Alexander. The trio will have their hands full with Kamara and the Saints, but they should be up to the task.

Slowing down Brees

I’ll be interested to see Saleh’s approach. Against the Packers, he had Tarvarius Moore on Aaron Jones and Jamal Williams, and aside from one play, Moore eliminated them. Dallas did something similar to the Saints earlier this season on Sunday Night football, but that was without Brees. Brees has thrown for under 250 yards twice this season. Those games both came against divisional opponents. What do the Bucs, Falcons, and 49ers defenses have in common? Team speed. The difference is you better bring your “lunch pail” when you play San Francisco, because not only are they athletic and can run, but this unit is as physical as it gets on defense.

Brees was sacked a ridiculous six times against the Falcons in the first matchup. The veteran quarterback has proven tough to bring down, as he’s only been sacked three times in the other games. Only Andy Dalton gets rid of the ball quicker than Brees, who is throwing the ball 2.37 seconds per attempt. That tells you everything is quick. Brees has thrown the ball over 20 yards only 19 times this season. When you look at where Brees has thrown the ball, 63% of his throws have come under ten yards. Twenty-one percent of the time, he’s throwing in between 10-20 yards. It’s not a dink and dunk offense, because the Saints skill players are turning these passes into explosive plays. New Orleans is seventh in explosive pass rate.

Oh, we’re talking pass defense? The 2016 Denver Broncos were historically the best pass defense at -31% per DVOA. The 2019 49ers defense is currently at -45%. If you think you’ve seen anything like them, you haven’t. I don’t think we’ve ever seen a defense where the pass rush and coverage were married together like San Francisco’s this year. The Ravens came into the game with arguably the most efficient and explosive passing game in the league, and Lamar Jackson finished the day with 105 passing yards and zero completions over 20 yards. On the season, you can put together an argument that the secondary has been better than the pass rush, and the pass rush has been the best in the league. Here are the success rates for the secondary:

Ahkello Witherspoon 74% (3rd)

Jimmie Ward 73% (4th)

Emmanuel Moseley 64% (11th)

Richard Sherman 58% (28th)

K’Waun Williams 56% (41st)

I’ve been keeping close tabs on defensive back play in the NFL since 2016, and I can’t recall the last time three players have been in the top-11 of success rate. Jaquiski Tartt is technically a safety so he doesn’t count, but he’s allowed five of his ten targets to be caught, but only for 30 yards. No team has allowed fewer explosive passes on the year. San Francisco has allowed 18 passes to be completed over 20 yards. The next closest team is the Rams at 23. This group is as stingy as it gets. The 49ers have allowed 85 passing first downs, which is the fewest in the NFL. The Niners defense has had six games this season where they’ve allowed 110 or less net passing yards. That’s tied for the most in a season in the NFL since 1980. It’s not me speaking in hyperbolic terms when I say this is legitimately one of the best pass defenses in NFL history.

The Saints love to move Michael Thomas around and rely heavily on him. They also will get Jared Cook involved, with the occasional shot down the field or outside of the numbers to Tre’Quan Smith and Ted Ginn Jr. Aside from that, it’ll be the Kamara show. We’ll get into matchups to watch before the game, but the Saints have had their worst performances against defenses that can run, have a cornerback to takeaway Thomas, and didn’t allow Kamara to get going. San Francisco is eighth in DVOA against No. 1 receivers. They are first in DVOA at defending running backs and allow the fewest yards per game, at 25.8. They are 11 percentage points better than the Bucs at limiting running backs. In a game that revolves around matchups, the Saints have the advantage of running the ball up the middle, but San Francisco holds the edge everywhere else.