Chicago Bears running back David Montgomery and Buffalo Bills running back Devin Singletary had very similar games on Thanksgiving Day. Both of their teams ended up winning on the national stage, and the two rookie running backs had nearly identical statistics on the ground. Montgomery rushed for 75 yards at 4.7 yards per carry, and Singletary rushed for 63 yards at 4.5 yards per carry. When you add in the fact that the two players combined for 50 receiving yards and two receiving touchdowns, they appear to have each had solid outings on Thursday. Based on those numbers, you might be considering playing either Montgomery or Singletary in your fantasy football playoff matchups next week.

Before you make that commitment, though, it is worth noting that both players also had very low PFN Offensive Share Metric (OSM) grades, indicating that there might be more to their rushing statistics than initially meets the eye. Montgomery’s grade of 9.01 was his third-worst grade of the season, although it does represent an improvement over a pair of somewhat abysmal performances in Weeks 11 and 12.

Singletary’s grade of 5.83 was his lowest of the year. These grades do not imply that the two players aren’t talented; that isn’t what the OSM is intended to measure. Instead, it calculates how much of a player’s statistical production they were directly responsible for. It was in this sense that the pair of rookies failed to perform, despite their more-than-passable statistics.

Explaining Montgomery and Singletary’s low OSM grades

In many circumstances, Montgomery and Singletary’s high yards per carry averages would result in high OSM grades. However, several other vital factors bring down those grades by a significant margin. The first of these is what the NFL refers to as a running back’s “efficiency rating.” This metric measures the average number of physical yards a running back ran for each yard they gained on the football field. To use some football colloquialisms, a player with a lower efficiency rating is more of a north-south runner, while a player with a higher rating is more of an east-west runner.

In their respective Thanksgiving games, Montgomery and Singletary averaged 3.35 and 3.94 yards of distance per yard gained, placing them somewhere in the middle. Those ratings aren’t particularly poor. In a vacuum, I would describe them as mediocre. However, when placed in context, they look significantly worse.

One scenario that can lead to high-efficiency ratings is when a running back faces a defense that is focused on defending the run and keeps more defenders near the line of scrimmage. When this scenario occurs, the running back might try to “make something happen” by extending the play in the backfield, often with limited success.

However, neither Montgomery nor Singletary were in such a position. In fact, at no point in either of their games did they face more than eight men in the box. In theory, they should have had plenty of space to find gaps in the defense. Despite this, they still only managed relatively mundane efficiency ratings, which indicates a lack of commitment in choosing running lanes, as well as the vision to find them in the first place.

To help illuminate the difference between Montgomery and Singletary’s performances, and those of a more successful running back, compare their numbers to those produced by the highest-graded running back from Thursday, Ezekiel Elliott. He had a better efficiency rating than either rookie, at 2.88, despite facing eight men around the line of scrimmage 33.33% of the time.

Unsurprisingly, that increase in efficiency resulted in both a higher OSM grade, at 23.46, as well as a yards per carry average 5.9 yards, more than a yard higher than either of the rookies. His efficiency as a runner allowed him to overcome more difficult circumstances than either Montgomery or Singletary faced.

To be fair, we shouldn’t expect either rookie to be playing at Elliott’s level yet. But if they hope to reach that level at some point, they will need to be far more efficient with their runs.

Looking at the future (and the fantasy playoff implications) for Montgomery and Singletary

So, what do Montgomery and Singletary’s low grades mean for the two running backs? From one perspective, not very much. Their teams both played well enough to win and allowed them to produce reasonable statistics. Therefore, you might be inclined to suggest that nothing needs to change. On the other hand, against stiffer resistance, their lack of efficiency could become a problem.

On Thanksgiving, the opposing defenses gave Montgomery and Singletary enough time to dance around in the backfield without completely ruining their production. However, against a defense that places more focus on defending the run, that style of running will almost certainly result in lower statistics. Unfortunately for the rookies, that time might arrive sooner, rather than later.

In Week 14, Montgomery and the Bears will face the Dallas Cowboys, who have the 15th best rushing defense in the NFL. That isn’t spectacular, but it still represents a significant increase over the 23rd ranked Detroit Lions defense that they defeated on Thanksgiving. Meanwhile, Singletary will face an even tougher challenge against the Baltimore Ravens third-ranked rushing defense, a massive increase in adversity after facing those aforementioned Cowboys the week prior.

All told, both rookies will be in far more difficult situations next week. And after Week 13 matchups in which they failed to make the most of what the opposing defenses gave them, Montgomery and Singletary could see a significant decrease in their production on the ground. Their teams might still win (although I wouldn’t bet on that in either case), but both players will need to be more efficient if they want to maintain their individual production, a fact that might be of particular interest to those playing fantasy football next week.

While fantasy football is a fickle game, it’s important to use all of the available information to piece the puzzle together. Given the not-insignificant risk that Montgomery or Singletary will regress in Week 14, I would think carefully before starting them in the fantasy football playoffs.