The difference between winning and losing in the NFL can sometimes be traced back to a team's performance in the red zone. It's where offenses can turn a good drive into a great one, and it's where defenses can save precious points by forcing field-goal tries rather than giving up touchdowns.

An efficient running back can be the difference between a touchdown or settling for a field goal. This article will not be focusing on the best red-zone runners, however. We will be looking at the five least-efficient backs in this area of the field in 2017.

We can figure out how efficient running backs were in the red zone by using our Net Expected Points (NEP) metric -- specifically Rushing NEP per carry.

NEP is what we use to track the efficiency of both teams and players with the team side being adjusted for strength of opponent. A three-yard conversion on 3rd and 2 is wildly different than a three-yard conversion on 3rd and 4, and NEP helps account for that by tracking the expected points players add to their team's total over the course of a season. You can learn more about NEP in our glossary.

To qualify for consideration, players needed to have had at least 20 red-zone rushing attempts in 2017.