It's hard out here for a running back, man.

According to numberFire's Net Expected Points (NEP) metric, rushing efficiency for backs decreased this year for the fifth consecutive season. You can chalk it up to injuries to the elite if you want, but things are trending in the wrong way fast.

This was more true for some teams than others. While running behind a bad offensive line can be like driving in a traffic jam, some dudes were in Los Angeles on a Friday afternoon. You can rev those Ferrari legs all you want, bruh, but you ain't going nowhere.

Let's see which teams struggled most with their rushing efficiency this year by looking at NEP. NEP measures the expected points added or subtracted on each rush, meaning a team won't be penalized for picking up a first down with a two-yard rush on 3rd and 1.

For each team, I looked at their success rate (the percentage of rushes on which their NEP increased) when rushing to the left, to the middle, and to the right. Then, each team was ranked from 1st through 32nd to each direction, with lower being better. I took the average of each directional ranking for each team to see which teams saw consistent struggles up front.

We clearly can't separate the running back from the offensive line here. However, based on what happened for the following six teams, they can use any method for improvements they can find. Let's dive in and see which teams are most hurting for help in their run blocking moving forward.

1. Houston Texans

Success Rate Ranks: 26th Rushing Left | 27th Rushing Center | 28th Rushing Right

You can pin this on Arian Foster's injury if you want, but things have gone south fast for the Houston Texans' rushing offense.

Including Foster, the Texans had three separate running backs who had at least 60 carries. All of them lost at least 11.75 Rushing NEP on the ground, and none had a success rate higher than 38.10 percent. It's possible that they're all just bad backs, but the offensive line clearly needs some help.

There has been plenty of buzz about the Texans potentially drafting Ohio State's Ezekiel Elliott, including in Mel Kiper's most recent mock draft. Based on this info, that may be the worst-case scenario for Elliott.

If the Texans don't address the offensive line in the offseason, it's hard to believe things will magically turn around with a new rusher in the backfield. Elliott can still have fantasy value because of the team's defense putting the offense in positive game script, but it would seem he would be better suited on a team a bit more adept up front.

2. Washington

Success Rate Ranks: 31st Rushing Left | 32nd Rushing Center | 17th Rushing Right

To Washington's credit, they did address the offensive line last year by selecting Brandon Scherff fifth overall. It just didn't translate into success on the ground.

Matt Jones is expected to take the reins as the team's top back with Alfred Morris hitting free agency, but both struggled to get going this year. Of the 44 running backs who had at least 100 rushes, Jones and Morris ranked 38th and 44th respectively in success rate. It's not permissible to show their rushing metrics to those under the age of 22.

As you can see above, no team was worse when running up the gut. Morris and Jones combined for 55 carries up the middle, resulting in -14.16 Rushing NEP and a 25.45 percent success rate. The team lost an expected two touchdowns on runs up the middle over only 55 carries. That's impressively awful.

It may not be fun to address the offensive line two years in a row, but Washington has a pretty serious need here. Without addressing the interior either via free agency or the draft, it's hard to see things getting better next year in the Washington backfield.

3. Indianapolis Colts

Success Rate Ranks: 29th Rushing Left | 20th Rushing Center | 29th Rushing Right

Yeah, yeah, Frank Gore is old. This one probably isn't all on the offensive line, but things were not pretty for the Indianapolis Colts.

Of all of the running backs who had at least 200 carries this year, Gore was the only one whose Rushing NEP per carry was less than -0.10. He was at -0.11, and the second worst (hello again, Alfred Morris!) was -0.08. That said, it's hard to pin all of the blame on Gore.

The other six running backs who got carries for the Colts combined to tote the rock 70 times; they turned that into -19.90 Rushing NEP and a 31.43 percent success rate, both worse per-carry marks than Gore. That should be indicative of more systemic issues than Gore's age.

4. Jacksonville Jaguars

Success Rate Ranks: 20th Rushing Left | 31st Rushing Center | 27th Rushing Right

The Jacksonville Jaguars also had the seventh-worst pass-blocking offensive line (based on Sack NEP per drop back), so things aren't looking too peachy up front here. Luckily, the Jags own the fifth pick in this year's draft, so they've at least got a shot to change that quickly.

Neither T.J. Yeldon nor Denard Robinson was abundantly successful this year, though Yeldon did fare a bit better overall. His -0.06 Rushing NEP per carry and 35.16 percent success rate were both below average, but they both topped the marks out of Robinson. That could be an encouraging sign if the team picks up some new pieces on the line.

The Jaguars haven't been negligent of the offensive line in recent drafts, selecting a lineman within the first three rounds each of the past three years. However, because they seemingly have some talent at the skill positions now, it can't hurt to keep hammering away on the big men up front.

5. New York Jets

Success Rate Ranks: 25th Rushing Left | 29th Rushing Center | 21st Rushing Right

Unlike the Jaguars, the New York Jets were one of the best pass-blocking lines in the league this year. That success just didn't translate to the ground game.

With both Chris Ivory and Bilal Powell set to hit free agency, the Jets may have to decide which is the better to keep. Powell -- though over a smaller sample size -- did best Ivory in both Rushing NEP per carry and success rate. When you add in his value in the passing game, that decision really shouldn't be too difficult.

The last time the Jets used a pick within the first two rounds on an offensive lineman was in 2010. That player was Vlad Ducasse, who has almost seven times as many penalty yards against him (151) as starts (22) in his career. It's likely time to change that so whoever ends up running the ball next year has something to work with.

6. San Francisco 49ers

Success Rate Ranks: 27th Rushing Left | 16th Rushing Center | 32nd Rushing Right

This was probably to be expected given everything that the San Francisco 49ers lost last offseason, including right tackle Anthony Davis. Looking at their success when running right, it looks like that loss made a teensy impact.

The 49ers ran the ball to the right 86 times this year. That resulted in -19.25 Rushing NEP, or -0.22 Rushing NEP per carry. The Texans were the only other team in the league that ended up below -0.15. This isn't an area where you want to be an outlier.

If we're looking for a bright spot here, it's that things were much better when Carlos Hyde was healthy. He had a success rate north of 48.0% when running both to the left and up the middle, though his numbers sagged when going right. If the team can keep him on the field and tighten up the right side of the line, this could turn around quickly.