Fantasy football players shouldn’t overlook the impact of offensive line play on running backs. But of course, rushing productivity isn’t a one-way street. NFL defenses aren’t created equally, and some defend the run better than others.

Traditionally, stats like yards surrendered and yards per carry against have been used to gauge the overall effectiveness of a defense against the run. However, a slightly more granular look has the potential to offer more insight into the best fantasy matchups for running backs.

When most people talk about the No. 1 run defense in the NFL, they’re referring to the rushing stats you’ll find on the various stat sections of some of the biggest sites on the interwebs. These stats rank defenses by total rushing yards surrendered.

2017 Run Defenses by Yards Surrendered RK Tm Yards RK Tm Yards 1 PHI 1,267 17 GB 1,793 2 MIN 1,337 18 DET 1,800 3 CAR 1,409 19 SEA 1,824 4 TEN 1,420 20 NE 1,836 5 DEN 1,430 21 JAX 1,860 6 ARZ 1,434 22 SF 1,861 7 CLV 1,566 23 TB 1,880 8 DAL 1,664 24 NYJ 1,887 9 ATL 1,665 25 KC 1,890 10 PIT 1,693 26 IND 1,927 11 CHI 1,730 27 NYG 1,933 12 OAK 1,743 28 LAR 1,957 13 HST 1,747 29 BUF 1,994 14 MIA 1,768 30 CIN 2,046 15 BLT 1,780 31 LAC 2,098 16 NO 1,787 32 WAS 2,146

It’s no surprise that the Eagles, Vikings, and Panthers paced the league. All three units were among the toughest on the run game for much of the 2017 regular season. But total yards really don’t do us much good unless every team faced the same amount of carries. To compare defenses on a per-play basis, yards per carry is a much more insightful stat.

2017 Run Defenses Yards Per Carry Allowed Rk Tm YPC Rk Tm YPC 1 DEN 3.3 17 ATL 4.1 2 CLV 3.4 18 MIA 4.1 3 ARZ 3.5 19 BLT 4.1 4 TEN 3.6 20 DET 4.2 5 MIN 3.7 21 NYG 4.2 6 PHI 3.8 22 CIN 4.2 7 SF 3.8 23 JAX 4.3 8 GB 3.9 24 TB 4.3 9 IND 3.9 25 KC 4.3 10 CAR 4.0 26 BUF 4.3 11 CHI 4.0 27 PIT 4.4 12 OAK 4.0 28 NO 4.4 13 HST 4.0 29 WAS 4.5 14 SEA 4.0 30 NE 4.7 15 NYJ 4.0 31 LAR 4.7 16 DAL 4.1 32 LAC 4.9

The Eagles, Vikings, and Panthers are still in the top 10, but Denver, Cleveland, and Arizona top the list. Likewise, you’ll notice that the Patriots drop from 20th in total rushing yards surrendered to 30th in yards per carry.

While this is interesting, we still aren’t getting the whole picture. Running backs operate best when they have space to run. The best way to measure that space is to look at yards before contact. We examined this stat on the offensive side of the ball, and observed some interesting correlations to running back productivity. Perhaps most notably was the dramatic turnaround of the Rams offensive line and the corresponding rebound in Todd Gurley’s performance.

Of course, some defensive units were better at limiting the space opposing running backs saw during the course of the season. Here’s the breakdown of yards before contact per attempt yielded in the 2017 regular season.

2017 Yards Before Contact Yielded Rk Tm YBCo Rk Tm YBCo 1 CAR 0.71 17 MIA 1.53 2 CLV 0.87 18 BLT 1.54 3 PHI 0.90 19 LAC 1.57 4 DEN 0.99 20 KC 1.60 5 ARZ 1.07 21 SF 1.61 6 TEN 1.15 22 SEA 1.62 7 ATL 1.25 23 HST 1.64 8 MIN 1.31 24 NYG 1.64 9 GB 1.31 25 TB 1.66 10 DAL 1.34 26 OAK 1.67 11 NYJ 1.36 27 NO 1.74 12 IND 1.44 28 PIT 1.76 13 DET 1.44 29 CHI 1.89 14 BUF 1.49 30 WAS 1.93 15 CIN 1.49 31 JAX 1.93 16 LAR 1.51 32 NE 2.20

Interestingly, the stingiest defenses in terms of yards before contact are a combination of the top units in yards surrendered and yards per carry allowed. Carolina allowed the fewest yards before contact per attempt, but the Browns were a surprising second-place on the list. The Browns were an underrated defense against the run for much of the 2017 season.

On the other side of this list, we have perhaps the most glaring disparity from the traditional measure of run defense. In the first chart, the Patriots come in as essentially a mid-pack unit. However, yards per carry allowed showed New England was much closer to the bottom of the league. When we look at yards before contact, the Patriots come in dead last and were the only unit this season to yield more than two yards before contact.

That ample room to operate was certainly in play in the Super Bowl. On runs from LeGarrette Blount and Jay Ajayi, the Pats allowed 1.78 yards before contact. While this was below their regular-season average, it still would have ranked worse than 28 teams in the league.

While this data is only a small piece of the fantasy puzzle, yards before contact has potential application in strength of schedule. Let’s now take a look at each offense and the average yards before contact allowed by their opponents from the 2017 regular-season schedule.

2017 Average Opposing YBCo Allowed Rk Tm YBCo Rk Tm YBCo 1 DEN 1.56 17 BLT 1.47 2 TEN 1.54 18 OAK 1.46 3 CLV 1.54 19 IND 1.46 4 ARZ 1.53 20 NE 1.46 5 NYJ 1.53 21 GB 1.45 6 CAR 1.52 22 NO 1.45 7 BUF 1.52 23 DAL 1.44 8 HST 1.52 24 NYG 1.44 9 KC 1.52 25 SF 1.43 10 PHI 1.50 26 CIN 1.43 11 MIA 1.50 27 SEA 1.43 12 MIN 1.48 28 JAX 1.43 13 LAC 1.48 29 DET 1.42 14 ATL 1.48 30 TB 1.42 15 PIT 1.48 31 WAS 1.40 16 LAR 1.47 32 CHI 1.35

There really isn’t a standout at the top of the list, though it is quite interesting to see Denver at the top. C.J. Anderson didn’t necessarily have a standout season, but he was one of just nine running backs to top 1,000 rushing yards.

Jordan Howard and Leonard Fournette also managed to crack the 1,000-yard mark. However, neither player was especially impressive on a yards-per-carry standpoint. Howard averaged 4.1 yards per tote, and Fournette posted an uninspiring 3.9 yards per carry. However, the above chart shows that both backs faced a tough slate of opponents this season. Likewise, Joe Mixon not only had to deal with a lackluster offensive line, but he also had a very tough draw in terms of the opposing defenses he faced.

Evaluating fantasy production isn’t a simple A-to-B process. There are many variables at play, and some have more impact on specific players than others. Yards before contact, both on the offensive and defensive sides of the ball, is one of those variables that should be considered as you build your draft boards for 2018 redraft leagues and draft teams in best-ball leagues.