One of the things I have been most fascinated with during this NFL season is the way teams are running the ball in a passing league. For the first time in several seasons, a number of teams have devised a method of running the ball in a way that is actually helping their offense, rather than hurting it. Allow me to explain.

According to Pro Football Reference, just four offenses in 2017 had a rushing attack that was beneficial to their team concerning "Expected Points" added. Those four teams were the Cowboys, Packers, Saints, and Browns. Every other team in the NFL had a run game that hurt their offense. Using that same metric, there are now 12 teams in 2018 that have rushing attacks that are beneficial to their offense. In one season, that's a pretty significant uptick in rushing efficiency.

How is that possible? For starters, teams are averaging significantly higher yards per carry than they were last season. Across the NFL, the average yards per carry is at 4.38. That is not only up considerably from 2017 (4.08), it’s the highest number in the last 20 years.

Since 2000, rushing efficiency is at an all-time high in 2018. pic.twitter.com/Mjv7psKMUg — Marcus Mosher (@Marcus_Mosher) November 14, 2018

Why has there been such a boom to the effectiveness of rushing attacks across the NFL? Have teams all of a sudden become better at running the ball than at any other point in the history of the league? Not likely. The actual answer is rather simple. Teams have figured out how and when they should run the ball.

Remember a few months ago when I wrote about Sean McVay’s offense and how he uses logic to defeat his opponents? The crux of that piece was that McVay will only run the ball when it’s in his favor to do so. McVay doesn't believe in running the ball just to keep balance or to set up the passing game. Instead, he will only run against defensive fronts that give him an advantage. That thought process and game theory is starting to become more mainstream in the NFL.

The more I study some of the best offenses in the NFL, the more I am blown away at just how smart they are compared to the rest of the league. The best teams in the league find a personnel grouping and exploit it. A perfect example of this the way the Rams have used Todd Gurley. On the season, Gurley has 198 carries out of "11" personnel (3 WRs, 1 RB, 1 TE). Can you guess how many carries he’s had in every other personnel grouping? Zero.

That's right. Every single carry Todd Gurley has taken this season has been out of "11" personnel — and for a good reason. Across the NFL, the average yards per carry out of "11" personnel is 4.91, per Sportradar. That is a significantly higher yards per carry than out of "12" personnel (2 WRs, 1 RB, 2 TE), (4.32) for example.

To me, it is pretty clear that the Rams are putting Gurley in a better position to succeed than most of the runners in the NFL.

Just because a player is put in a better situation to make plays doesn't necessarily make him a better player than the rest of his peers (I do think Gurley is outstanding, by the way).

As a whole, the media and fans still don’t have a good metric to judge running backs other than using basic counting stats. That’s why we have introduced “success rate” to help determine which running backs have the most significant impact on their teams. However, even "success rate" can be a noisy stat depending on what personnel grouping a team decides to use the most.

Today, I want to provide some context to how teams are running the ball by showing the raw stats and success rate from a few different personnel groupings.

Let's start with the most common personnel package in the NFL — "11" personnel. With the league becoming more pass-heavy, having three receivers on the field at all times is a must. In turn, that means defenses have to counter with their nickel packages, often leaving only six defenders in the box to stop the run. So this is why running out of "11" personnel has yielded such great results.

According to Sportradar, 48.5 percent of runs this season have come from "11" personnel. That is a significantly higher percentage than in any other season. That makes sense to me because of the overall success of the package. Let’s take a look at how often and how well some of the top runners in the league are performing out of "11" personnel groupings, sorted by success rate. Take a look:

It might surprise you that Todd Gurley doesn't have the highest success rate or even yards per carry out of "11" personnel this season. What I found surprising is just how many more carries he's had out of that personnel grouping than the rest of the league. No other runner in the NFL has even 100 attempts out of "11" personnel. Gurley has doubled even the next highest (James Conner). As great as Gurley's stats have been this season, they are a little inflated by to the offense he plays in and his coaching staff's brilliance.

As I mentioned at the beginning of this piece, "11" personnel produces higher yards per carry than "12" personnel (and most other personnel packages as well.) Below is a chart of the top runners in the league, sorted by success rate out of "12" personnel. Though the success rate is similar for the top running backs, take a peek at the average yards per carry in comparison to those in "11" personnel:

A player like Kerryon Johnson is dominating out of "11" personnel but is having far less success in "12" personnel. If the Lions decided to only run Johnson out of "11" personnel, we might be having a different discussion in regards to this season's Offensive Rookie of the Year. That's just one of the many examples of how personnel groupings and usage impacts our thoughts and opinions on a player.

Over the past several months, there has been a push by the analytical community to say that "running backs don't matter" or that they are "replaceable." I've been active in those arguments, but in this case, it's not the point. Instead, what I am saying is that a running back's success is often dictated by how they are used, rather than just pure talent. Bad offensive coordinators or schemes can cripple even the best runners in the league.

Todd Gurley is the perfect example of this. In 2016, a majority of his carries were not in "11" personnel (just 121 total carries out of "11" that season). Instead, Jeff Fisher and the rest of the coaching staff insisted on using him as a battering ram (pun intended) against stacked boxes and with multiple tight ends and fullbacks on the field. What happened to Gurley that season? His yards per carry dropped to 3.18, and we all wondered if he was going to be a bust for the Rams.

However, with Sean McVay, Gurley is an MVP candidate. Did Gurley all of a sudden become a much better runner? Of course not. The situation around him improved. And that's the point of this piece. Situations matter. NFL teams are recognizing this, and this is why you are seeing more efficient rushing attacks across the league. In general, running backs haven't gotten better at running the ball. Instead, some teams are just now learning how to do it more effectively.