Minnesota Vikings rookie running back Alexander Mattison is currently backing up the NFL’s leading rusher, Dalvin Cook. Cook has received a significant amount of praise, consistently being discussed as one of the best running backs in the NFL. However, his PFN Offensive Share Metric (OSM) grades have been mediocre at best. Mattison, on the other hand, has been graded very highly in his limited opportunities. While it would be a stretch to claim that Mattison is better than Cook, he certainly has performed better than his teammate in a number of advanced metrics.

Examining running backs with the OSM

To be clear, the PFN OSM is not a measure of a player’s individual skill. Instead, it calculates how responsible a player was for their offensive production using the NFL’s Next Gen Stats. For example, a quarterback that gained most of his yards on screen passes would receive a lower grade than one that completed multiple deep passes. There are three statistics in particular that help to explain why the OSM graded Mattison better than Cook: yards per carry, running back efficiency, and defenders in the box percentage. Most football fans are familiar with yards per carry, but the other two metrics might be new to you.

Running back efficiency measures how many physical yards a player ran for every yard they gained in total. A running back that primarily ran straight ahead would have a significantly lower grade when compared to one that ran horizontally across the field. So, a player who totaled 85 yards rushing, but ran a total of 506 yards in order to do so, would have a relatively poor efficiency rating of 5.95.

The other metric, the defenders in the box percentage, is less complicated. The NFL tracks how many defenders are at or near the offensive line at the time of the snap. More specifically, for our purposes, the NFL measures how often a running back saw eight or more defenders in the box as a percentage of their total snaps played. That percentage helps us to gauge how much resistance a player saw whenever they touched the ball.

Comparing Mattison and Cook’s performances

Mattison received enough carries to qualify for an OSM grade in Weeks 3, 6, and 8. In Week 3, he was not particularly impressive. He averaged 4.8 yards per carry, but had an unimpressive efficiency rating of 3.8 and only saw eight defenders in the box 8.33% of the time. Those mediocre statistics resulted in an equally mediocre grade of 12.14 – 16th among qualifying running backs that week.

In that same game, Cook outperformed Mattison in all three categories. He averaged an excellent 6.9 yards per carry and maintained an efficiency rating of 3.2 despite facing eight defenders in the box more than ten percent more often than Mattison. His resulting grade of 18.95 wasn’t anything special, but it still represents a significant increase over his backup.

However, in Weeks 6 and 8, the comparison was reversed. Week 6 against the Philadelphia Eagles was Mattison’s best performance. He received a grade of 38.37, the highest grade received by any running back so far this season. That more than doubled Cook’s grade of 15.50. Cook’s low grade is relatively easy to explain. He was one of the week’s least efficient runners, with a rating of 6.32, and averaged a paltry 2.6 yards per attempt. The only reason his grade wasn’t lower was the fact that he saw eight or more defenders in the box 37.5% of the time, a higher percentage than all but two other players.

One of those players was Mattison, who was in a similar situation a ludicrous 85.71% of his snaps, the highest percentage faced by any running back so far this season. Despite those difficult circumstances, he still had a respectable efficiency rating of 4.24 and 4.5 yards per carry. Put simply, both Mattison and Cook were placed in challenging situations, but Mattison’s were generally worse, and he nevertheless outperformed Cook by a significant margin.

The story in Week 8, against the Washington Redskins, was roughly the same. Mattison received another high grade of 26.61. The full grades from this week are not calculated yet, but for a rough comparison, that grade would have been the second-best of any running back in Week 7. Once again, Cook’s grade was a relatively poor 15.67. The same factors involved in Week 6 helped create the discrepancy in Week 8 as well. Mattison was more efficient (3.67 vs. 4.38), averaged more yards per carry (4.7 vs. 4.3), and once again faced eight or more defenders in the box a higher percentage of the time (46.15% vs. 26.09%). The differences were smaller but still very noticeable.

The Vikings are in a phenomenal position at running back

The fact that Mattison has performed better than Cook according to the OSM does not mean that he is a better player overall. I am in no way suggesting that the Vikings should replace Cook as the starter. These three games represent a relatively small sample size. As the season progresses, we might see Mattison regress. Additionally, OSM grades for running backs do not take into account their receiving production, an area in which Cook has a substantial advantage. In Minnesota’s win over the Redskins, he caught five passes for 73 yards and a touchdown. Meanwhile, Mattison has three receptions all season.

What the metric does show is that, given the circumstances he was presented with as a runner, Mattison has done a significantly better job of maximizing those opportunities than Cook has. Fortunately, the Vikings do not need to make hard decisions any time soon. Both players are still on their rookie contracts, so, for the time being, they continue to split carries between the two backs. Assuming Mattison isn’t cut or traded, Minnesota will have an excellent one-two punch at running back for the next several years.


  1. I DUNNO where this writer comes from but he’s really terrific. Incisive use of statistics analysis in a style that reminds me of the clarity of storytelling of a post-modern Bob McGin or Dick Schaap.

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