Football Outsiders released a nice little teaser for their 2014 Almanac last week by breaking down offensive personnel groupings in the NFL last year. Their findings are very interesting, and back up the commonly accepted idea that NFL offenses are "spreading things out" with three- and four-wide looks more often than ever before.

Per FO's Aaron Schatz, in 2013, "teams came out in 11 personnel (3WR, 1TE, 1RB) on a majority of plays: 51.2 percent. They came out with three or more wide receivers on 58.8 percent of plays." That's up a significant amount (skyrocketed, in Aaron Schatz's words) as compared to the previous year, and the year before that, and there's a simple reason for it.

It works.

That makes sense.

Look at how more efficient offenses were with 11 personnel last year (link). This isn't a one-year fluke. In 2012, the leaguewide DVOA with 11 personnel was also 8.1%. In 2011, it was 5.5%, and in 2010, it was 9.1%. Right now, the most efficient way to play offense in the NFL is to put three wide receivers, one running back, and one tight end on the field with your quarterback in shotgun for a majority of snaps. Not all of them, you have to switch it up of course, but most of them.

The Seahawks, a run-heavy "old-school smashmouth" team, were not a huge outlier in this I don't think, and while they used two tight end sets or two back sets with fullbacks more than the average bear, they did run with 11-personnel in shotgun formations quite a bit. I'm guessing that once the FO Almanac is released, it will show that 11-personnel was their most efficient grouping from a DVOA standpoint, as well.

Here's why: the three wide receiver personnel grouping allows the Seahawks' offense to put its best five playmakers on the field at one time. Last year, it was Marshawn Lynch at running back, Zach Miller as a blocker and receiver in-line, Percy Harvin in the slot or running amok on fly sweeps, and Golden Tate and Doug Baldwin outside (Jermaine Kearse was in the mix when Harvin was out, and of course the team rotated players at different spots).

Making them more unpredictable, all of Seattle's receivers could line up at any spot on the field, inside or out, and Miller was versatile enough to, at times, line up as a de facto fullback or slot receiver. There are hundreds of formations that you can use out of 11-personnel, and Seattle was very multiple.

The use of the 11 personnel grouping skyrocketed because it puts a defense in a bad position, as long as you are a balanced enough team.

For Seattle, if the defense plays Cover-2, at least one of the three (or four) receivers will be in single coverage, either outside or up the seam. Here's an example -- Percy Harvin's route up the numbers draws the attention of the slot defender and the safety to his side. This allows Doug Baldwin to get to the corner of the endzone vs. single coverage. The safety is not quick enough to adjust.

A typical Cover-2 defense against this personnel would dictate putting four defensive backs in the secondary and, likely, a nickel back or linebacker lined up against the slot receiver. This means that you're seeing a six-man box, which also means it's easier to run, in theory.

Seattle likes this. In 2012, 11-personnel was the Seahawks' most effective grouping for running. It was and is their most common "read-option" grouping. The 2013 numbers are not out yet, but I'd guess this holds true.

Now, against a Cover-3 defense, you'd see a single high safety and two corners outside. Against this, you'd have at least two of the three receivers in single coverage either outside or up the seam. You'll see an extra safety in the box to help stop the run, but you'll get those one-on-one match-ups outside or up the seam that you're looking to pass against.

Again, there's a great example from the Minnesota game. It's not in 11-personnel, here the Seahawks are in 21 personnel with a fullback swapped in for tight end Zach Miller, but the principles of having three receivers in the game still apply. The Vikings stack the box with eight defenders to try and stop Marshawn Lynch.

*****

Going forward for Seattle, in 11- or 12-personnel, with Percy in the slot, Baldwin and Kearse (or maybe Paul Richardson or Kevin Norwood) capable of winning one-on-one on the outsides, opposing defenses will likely play you in Cover-2 more often than not. Because Seattle wants to run, this is a good thing. Fewer people crowded into the box means Lynch can do his thing. Add in Russell Wilson's mobility on bootlegs or option plays and Percy Harvin's laterally-stretching fly sweeps, and the Seahawks create a mathematical advantage for the offense.

Now, Seattle will still mix up their formations and still like to use a fullback on maybe 30% of their snaps. A lot of the time, as we've seen, Seattle is asking teams to load up the box with an extra safety because it gives them one-on-ones downfield on play-action passing. Marshawn Lynch's toughness and tackle breaking ability means Seattle can really force an opponent's hand -- "you have to bring up your guy when we're running two-backs or two tight ends. You have no choice." At the end of the day, they want to dictate, not react.