This article is part of a series in which I evaluate 2022 rookie running backs solely on their ability to run the ball. The first installments can be found here. I’ve changed up my methodology a bit since publishing those articles, which I go over in detail in this process-focused piece. I’ll give a quick refresher below, but also feel free to skip straight to the player-focused analysis below the picture of Alabama’s Brian Robinson a couple paragraphs down.
Outside the ability of whoever happens to be running the ball, there is a whole mess of variables that factor into the effectiveness of a given rushing attack: scheme, play-calling tendencies, opponent strength and scheme, weather, offensive line play, surrounding skill-position talent, etc. And given this entanglement, separating the contributions of the ball carrier from the offensive environment in which he operates is not a straightforward task. My approach to doing that is centered around measuring the degree to which a running back is over- or under-performing the per-carry output of the other running backs on his team.
Starting from the premise that good runners do more with what they are given than do bad runners, it stands to reason that, provided players are operating under generally the same conditions (like, for example, playing on the same team), better backs should produce more per carry than lesser backs. Using this logic, we can establish a baseline for comparing efficiency between players on the same team; for each running back, we can compare his performance (X) to the collective performance of every other running back on the team (Y). If X > Y (essentially, if dude is doing more with his carries than his teammates are with theirs), we can probably conclude that the player in question is a good player, at least to some relative degree.
Assuming that this is a sound method of evaluating running backs relative to their teammates, we can then extend our comparisons to players from other teams (we’re really just creating a baseline for efficiency comparisons similar to how Dominator Rating and other market share-based metrics create baselines for volume-based comparisons).
The key metrics I use to evaluate running back performance vs. that of their teammates are called Yards Per Carry+, Chunk Rate+, and a metric I developed recently called Box-Adjusted Efficiency Rating, or BAE. I also like to use a metric called Breakaway Conversion Rate, but that is not a teammate-relative measure and we’ll therefore look into it separately.
The metrics are pretty straightforward: YPC+ is the degree to which a player over- or under-performs his teammates in yards per carry, and Chunk Rate+ is the degree to which a player over- or under-performs his teammates in rate of “chunk” runs (which I classify as runs of 10 yards or more). At a basic level, I want my running back prospects to find a way to produce more per carry than the other backs on the team, and part of that puzzle is navigating the line of scrimmage and extending runs into the secondary at a higher rate than his backfield mates. YPC+ and Chunk Rate+ measure the degree to which a player does both of these things.
BAE also does those things, but it improves upon Yards Per Carry+ by using a weighted average of a player’s per carry efficiency on carries vs. various amounts of defenders in the box (using data from Sports Info Solutions), relative to the per carry efficiency of other running backs on his team vs. the same box counts. The resulting percentage indicates to what degree a runner over- or under-performed his teammates on his total rushing attempts, relative to how often he faced each box count. BAE is a more comprehensive metric than is YPC+, and I will defer to it accordingly, but YPC+ and Chunk Rate+ will still be used given that the sample of data I have for those metrics goes back a decade-plus (while I’m only able to generate BAE Ratings going back to the 2018 college football season).
Brian Robinson had to wait a long time to take over the backfield at Alabama, but when he finally did as a fifth-year senior in 2021, he made the most of it, producing over 1,600 yards and scoring 16 touchdowns. Unfortunately, he happened to make the least of his opportunity to run the ball efficiently at pretty much every point in his career.
Things started out good for Robinson from an efficiency standpoint. He outproduced a very talented running back group (their average rating as high school recruits was 4.25 stars, a 91st-percentile number among teammates of backs drafted since 2007) by 0.79 yards per carry and a massive 11.95-percent in Chunk Rate (if those were career marks, they’d be in the 61st and 99th-percentiles, respectively) as a true freshman. That was only in spot duty on 24 carries, but encouraging nonetheless. And then the wheels fell off.
Over the next three years, the absolute best YPC+ mark that Robinson managed was the -0.55 he posted in 2020, while his best Chunk Rate+ — a -2.83-percent mark — came in the same season. Contrasted with his freshman numbers, these marks would be in the 15th and 16th-percentiles, respectively.
In his only season as Bama’s starting back, Robinson was more efficient than the other runners on his team for the first time since he was a first-year player, but he still wasn’t good. On 271 carries this last year, he posted a 34th-percentile YPC+ of 0.14 and a CR+ of 1.59-percent that would land in the 57th-percentile. Over 545 carries for his career, he lagged behind his backfield mates by 0.37 yards per carry (18th-percentile) and 0.90-percent in Chunk Rate (21st-percentile). He was also terrible in the open field, converting just 14.3-percent of his 10-yard gains into 20-yard breakaways, a 3rd-percentile display of big-play ability.
Robinson put all this on wax while facing lighter average box counts than other Tide backs, with 0.07 fewer defenders in the box over his career than his teammates saw, a 31st-percentile discrepancy. As you would expect, his per carry output remains atrocious when you account for the box counts he saw, as his career BAE Rating is just 82.1-percent, the second-worst score I’ve encountered so far. He was simply awful relative to his teammates against every individual box count he saw, as his best output came against 6-man boxes, where he produced 90.4-percent the per carry average of other Alabama running backs. If it were his overall score, that 90.4-percent would itself be the second-worst BAE Rating of any running back in the 2022 class.
RUSHING EFFICIENCY SCORE AND COMPS
Simply put, Brian Robinson is one of the worst pure runners of any back in this draft, and his score in my running back model’s Rushing Efficiency composite (which accounts for all the non-BAE metrics touched on here in addition to overall team quality, offensive line play, strength of opponent, and rushing volume) reflects that. He earns just a 32.6 out of 100 there, the third-lowest in the class. In a BAE-centric composite rating that I’m workshopping, he earns a 25.7, rock bottom for 2022 backs.
My model also generates comps, and of particular interest to us here is the “pure runner” category, which accounts for all the metrics that go into the Rushing Efficiency Score as well as physical attributes like height, weight, and athletic testing numbers. Robinson was 226-pounds and nearly 6-2 at the Senior Bowl, and for our purposes here, we’ll assume he runs a 4.50 in the forty. Given those numbers, here are his most similar prospects as pure runners:
We have surprise cameos here by not-awful players like DeMarco Murray and Josh Jacobs. Murray is here despite being more efficient than his college teammates because he also played at a blue blood school, was bad in the open field in college, and is essentially the same size as Robinson, while Jacobs is here because Robinson is essentially a worse version of the overrated prospect that Jacobs was a couple years ago. The highlight of the rest of the list is T.J. Yeldon, which probably speaks for itself.
Just for fun (and in case you’re willing to cut him some slack since he played at such a powerhouse program), here’s Robinson’s rushing efficiency profile next to every running back drafted out of Alabama since 2007, sorted by Composite Score:
Brian Robinson is simply a very bad prospect with very bad rushing efficiency numbers, even compared to other guys who had to compete with other talented players in the same program that he did. If you’re latching on to him as some sort of sleeper in this year’s running back class, you may as well as just light a taxi squad spot on fire. He’s not good.