49ers-Saints NFL Divisional Round Preview: A Football Outsiders Statistical Supplement

Hello again everyone. My statistical preview of today's 49ers-Saints game is up on Football Outsiders, so feel free to click over there, and give it a read while you eagerly anticipate kickoff. I didn't have enough space in that article to go over every last bit of statistical matchup minutiae, and David asked me to contribute to the Niners Nation playoff euphoria, so here I am, ready to drop some supplemental knowledge.

Let's start with something that a lot of people have been talking about this week: Is the Saints offense really that much worse of a team on than the road than at home? At Football Outsiders, we rate teams according to an efficiency statistic called DVOA (current ratings are here, methodology is here), which evaluates the success of every play, and adjusts the team's success points according to the strength of opponent (e.g., it's easier for an offense to convert 3rd-and-15 against the Rams defense than the 49ers defense) and the type of game situation (e.g., it's easier for a defense to stop 3rd-and-15 than 3rd-and-1). Because DVOA is a play-by-play metric, we can aggregate it into whatever stat split we want to evaluate.

In this case, the relevant split is home-road, and DVOA indicates that, yeah, the Saints offense is a lot worse on the road. Specifically, the difference between their efficiency at home and their efficiency on the road is the third-highest in the league this season. Now, don't get me wrong, New Orleans No. 1 offense at home only drops to fourth-best on the road, so it's not like we're talking about San Francisco circa 2010 (15th at home, 30th on the road). Nevertheless, when it comes to ratings rather than rankings, what we are talking about is a unit that can't be stopped becoming one that can at the very least be slowed down.

This is even more intriguing given that the 49ers defense has exhibited an almost-identical type of home-road DVOA split. Namely, they're No. 2 at home, No. 9 on the road, and their home-road efficiency difference is seventh-highest among NFL defenses. So, putting the Saints' and 49ers' home-road splits together, what initially appears to be a 4.3 percent New Orleans advantage in overall efficiency becomes a 24.7 percent San Francisco advantage when we take the game's venue into account. That's a big difference!

After the jump, more matchup knowledge...

OK, so that was a stat in favor of the 49ers. Now, here's one in favor of the Saints: Their offense is ranked fourth in DVOA on short passes (i.e., 15 air yards or less), and San Francisco's defense ranks only 17th in defending them. Seventeenth might not seem all that bad, except when you consider that their defense is ranked No. 1 in the NFL on deep passes. It also doesn't help that 83 percent of New Orleans' passes this season have been of the short variety, which is fifth-most in the league. In other words, Sean Payton likes the short passing game, Drew Brees and co. are really good at it, and it's a relative weakness for the 49ers pass defense.

Next up is another stat that favors the Saints, but everyone reading this will wish the shoe was on the other foot. Specifically, New Orleans offense is No. 2 in red zone passing, whereas San Francisco's defense ranks 25th. The silver lining here, though, is that the 49ers are very good at keeping their opponents out of the red zone, having faced the fifth-fewest red zone plays (61) of any defense in the NFL. A good part of the reason why offenses don't reach the red zone against San Francisco is because they're No. 1 in defense DVOA from their own 20 to their own 40 yard line.

Alright, now let's turn to some more in-depth stats. At Football Outsiders, we have a game charting project wherein a group of about 30 volunteers (and staff members) watch every play of every game, and mark down a bunch of information about each play. Things like formations, offensive and defensive personnel, blown blocks, broken tackles, pass pressures, etc. It's incredibly labor-intensive, so we don't have the entire season done yet. We do, however, have most of it done, which means I can share some results with you here that actually mean something.

Below you'll find two tables. The first shows the personnel groups that New Orleans uses at least 5 percent of the time in non-blowout situations, along with how often they use it (FREQ), their success rates (SR) for each personnel group, and San Francisco's corresponding SRs that they've allowed on defense. The second table is the same thing, just from the perspective of the 49ers offense.

One quick note of clarification: We count players according to where they line up in the formation, regardless of what their official roster position is. The only exception is that tight ends lined up as slot receivers are counted as tight ends, not wide receivers.

Check out the difference in the 49ers' pass SR allowed between the 0-4-1 and 1-3-1 personnel groups. Seems clear, then, that if the Saints are going to spread it out and throw it, they're better off doing so with four-wide than with a one-back, three-wide alignment.

First thing you'll notice is that there are only four formations in this table, as opposed to the six for New Orleans offense. That doesn't mean, however, that the 49ers offense lacks personnel/formation diversity. On the contrary, as I mentioned in the Football Outsiders article, they've actually used the most number of different personnel groups in the league (22). So, the reason only 4 of the 22 are listed here is because the Niners actually have a handful of groups they use a lot, and then a veritable cornucopia of atypical groups that they pepper in more selectively. For instance, these are my personal favorites that I've seen them use: 1-0-2 with seven (!!!) offensive linemen, 3-0-1 with six offensive linemen, and 3-2-0 with Sopoaga in the backfield.

The other thing that jumps out from the table is that the Saints have had a hard time on defense stopping a 2-RB, 1-WR, 2-TE formation, regardless of whether we're talking run or pass. So, the odds are pretty good that you'll be seeing the 49ers run at least 10 plays with Frank Gore (or Kendall Hunter) and Bruce Miller in the backfield, Michael Crabtree split wide to one side, and both Vernon Davis and Justin Peelle at the end of the line on the other side.

To finish things up, one other thing we mark down as part of our game charting is the player (or players if it's double-man) with coverage on an intended receiver. Below are two tables showing the defenders you're most likely to see in coverage today, their yards allowed per pass play (Y/P), the average air distance of a pass thrown to their coverage responsibility (PYD/P), their average yards allowed after catch (YAC/C), and the SR allowed on plays where they covered the intended receiver (SR ALL). Both tables are ranked from best to worst SR ALL.

Bottom line: Avoid Jabari Greer on the outside, but attack the short middle and short right!

Dashon Goldson likes to gamble, and gets burned for it plenty. New Orleans will no doubt try to use his aggressiveness against him. Given how good Patrick Willis and Carlos Rogers are in coverage, the Saints will probably send Jimmy Graham in Goldson's direction (or even Chris Culliver's) instead, and send Darren Sproles in NaVorro Bowman's direction most of the time.

Well, that's it for this week. Hopefully, between my preview on Football Outsiders, and the extra info I've presented here, you're primed and ready to watch the chess match between Sean Payton/Pete Carmichael and Vic Fangio on one side of the ball, and between Jim Harbaugh/Greg Roman and Gregg Williams on the other. It should make for fascinating football. Here's to it being 49ers winning football!!!