Matt Forte retired yesterday, but we will leave those thoughts for another post. Today, I want to look at what I’ve referred to before as special teams yards. What are those?

All yards gained on special teams are done outside of the context of the series (down and distance) environment that defines most games. A kickoff return from to the 30 or to the 40 represents a difference of 10 yards, but those 10 yards are not as valuable as the difference between a gain of 5 yards and 15 yards on 3rd-and-10. The former are, quite literally, special teams yards. They don’t provide any value in gaining any additional first downs, or keeping a drive alive. Special teams yards, while obviously valuable, are — just as obviously — the least valuable yards possible. On a 3rd-and-10, a 15-yard pass provides a significant amount of value by providing a first down. But let’s get a bit more precise: the first 10 of those yards were really valuable. The last 5? Well, those were special teams yards. The difference between gaining 10 yards and gaining 15 yards on 3rd-and-10 isn’t that significant: well, it’s about as significant as returning a kickoff for 30 yards or 35 yards. Those last 5 yards don’t help a team move the chains.

So all yards gained by a player after already picking up a first down are what I’m referring to as special teams yards. And you know what other yards are less meaningful? All yards on third down or fourth down (special teams yards can come on any down) that don’t pick up a first down. A 9-yard run on 3rd-and-15 are just like special teams yards, too.

So let’s call all yards gained after gaining a first down “Post-1D Yards” and all yards on 3rd or 4th down that don’t go for a first down “3D Fail Yards.” To be clear, I’m not saying that Post-1D Yards or 3D Fail Yards are meaningless, but they are akin to special teams yards because they don’t help move the chains. They are yards gained outside of the context of the goal of acquiring a new set of downs.

Now, let’s talk about Forte, who rushed 103 times for 381 yards last year, which equates to 3.70 YPC. His backfield teammate, Bilal Powell, rushed 139 times for 754 yards, a 4.34 YPC average. But Forte had almost no “special teams” yards: he had just 35 yards picked up after gaining a first down, and only 4 yards gained on failed third/fourth down rushes. If you eliminate those, his “net” yards per carry was 3.32.

As for Powell? He had runs of 41, 51, 57, and 75 yards, along with five other runs of at least 20 yards. Those contributed to the 267 Post-1D Yards that Powell had, which comprised a whopping 40% of his total rushing yards. That was the third highest percentage in the NFL (minimum 100 carries) behind only Kenyan Drake (41%) and Cam Newton (43%). Meanwhile, Forte had just 9% of his rushing yards come as Post-1D Yards, the lowest in the league (Jamaal Williams was second at 12%, followed by Doug Martin at 15%). And in addition, Powell had 4% of his yards come as 3D Fail Yards, compared to just 1% for Forte.

Add it up, and Powell’s “net” yards per carry after removing “special teams” yards was just 2.44, quite a bit behind Forte. The table below shows the full data set for all rushers with 100 carries in 2017:

What stands out to you?

Two notes. The correlation coefficient between Net YPC and actual YPC is 0.61, which is pretty low considering about one-third of actual YPC comes from the elements we leave out of Net YPC (i.e., Post-1D Yds and 3D Fail Yards make up about 33% of total rushing yards). The correlation coefficient between yards per carry and Post-1st Down Yards is 0.66, which is a good reason why, in my opinion, yards per carry isn’t all that helpful in understanding team success.