2022 Chargers Backfield Breakdown: Sidekick Tryouts

by Noah Hills · Analytics & Advanced Metrics

The 2022 Chargers Backfield Breakdown is part of an offseason series in which I take a deep dive into one NFL team’s backfield and examine the respective rushing performances of the players in it. In doing so, I hope to gain insights into key players from a talent evaluation standpoint, and using that evaluation as a baseline, from a dynasty valuation standpoint. The first installments in the series can be found here.

I’ll start by taking a quick overview of each team’s raw rushing volume and propensity to run the ball in general, and then dive into the player evaluation portion. Before we start, let’s define the metrics I’ll use as part of those evaluations:

Key Metrics

Yards per Carry+ (or YPC+)

The degree to which a player’s raw yard per carry average exceeds or falls short of the collective yard per carry average of all other running backs on his team. Meant to be an overview of a player’s team-relative efficiency.

Box Count+

The degree to which the average amount of defenders in the box that a player faces on his runs exceeds or falls short of the collective average faced by the other running backs on his team. Considering that the outcome of any given rushing attempt is largely dependent on the amount of defenders in the box pre-snap, Box Count+ describes the relative degree of difficulty of a running back’s carries.

Breakaway Conversion Rate (BCR)

Quantifies performance in the open field by measuring how often a player turns his chunk runs of at least 10 yards into breakaway gains of at least 20 yards.

Box-Adjusted Efficiency Rating (BAE Rating)

Improves upon YPC+ by accounting for the box counts that a player carried the ball against. Looks at team-relative yards per carry against each individual box count, then uses a weighted average (based on total carries against each box count) to generate an overall score. A score of 100-percent indicates that a player is producing exactly the per carry output of his teammates, a score above 100-percent indicates that he is outdoing their per carry output to whatever degree, and vice versa for a score below 100-percent.

Relative Success Rate (RSR)

Measures player consistency using Success Rate, but relative to his teammates and adjusted for the box counts that he faced in the same way that BAE Rating is. “Success” on a given carry is defined by gaining 40-percent of yards needed on first down, 70-percent of yards needed on second down, and 100-percent of yards needed on third or fourth down. A score of 0.0-percent indicates that a player is succeeding on exactly the same percentage of his carries as are the other backs on his team, a positive score indicates that he is succeeding more often than his teammates are, and vice versa for a negative score.

Volatility Rating

Measures the disparity between a running back’s percentile ranks in BAE Rating and RSR in order to indicate how volatile a player’s per-carry performance is. High overall efficiency paired with low rate of success indicates boom/bust output, while low overall efficiency paired with high rate of success indicates steady, low-ceiling output. Measures degree of volatility, not quality of performance.

Composite Efficiency Score (CES)

Presents a single-metric overview of the quality of team-relative performance a player produced on his carries in a single season. Calculated using the average of a player’s percentile ranks in Box-Adjusted Efficiency Rating and Relative Success Rate, represents player performance on a 0-100 scale.

Team Rushing Volume

The Los Angeles Chargers finished No. 23 in the NFL in rushing attempt volume last season. Their 423 carries were nearly 30 fewer than league average in the first year of the Brandon Staley era. This after ranking No. 9 in the league in the same category under Anthony Lynn in 2020.

According to data from rbsdm.com, it seems the team’s low rushing volume from a year ago was the result of a philosophical commitment to throwing the ball. They had the fifth-lowest early-down run rate in neutral Game Script situations (when win probability for either team did not exceed 80-percent) last season. They also opted to throw the ball more often than expected (given league-wide play-by-play data) in nearly every down-and-distance situation, and 4-percent more than expected overall.

We only have one season’s worth of decision making from which to draw conclusions about the way that Staley and offensive coordinator Joe Lombardi want to run this team. But with Justin Herbert at quarterback, it seems reasonable that they would continue to be a pass-heavy team going forward. Lombardi’s previous stint as the offensive coordinator in Detroit from 2014-2015 saw the Lions also have the fifth-lowest early-down, neutral Game Script run rate. This is a team with both the propensity and the personnel to air it out.

Efficiency Numbers

Austin Ekeler was the clear leader in this running back room. But three other guys, Justin Jackson, Larry Rountree, and Joshua Kelley, all saw nontrivial work on the ground in 2021. Here are the complete rushing efficiency profiles for each of those backs:

Ekeler was one of the best runners in the league last year. His 79.4 Composite Efficiency Score ranked No. 5, ahead of players like Alvin Kamara and Joe Mixon.

Ekeler has a reputation as a space back who isn’t a traditional between-the-tackles guy. But he was tremendous in short-yardage and obvious running situations last year. On 53 carries against 8 and 9-man boxes, he posted a 156.5-percent Box-Adjusted Efficiency Rating and succeeded on 16.8-percent more of his attempts than did the collective other backs in Los Angeles.

Ekeler has posted BAE Ratings above the 100-percent mark in every season of his career for which box count data is available. He’s posted positive Relative Success Rate marks in three of those four seasons.

Jackson was an effective second option, posting his third straight season with a BAE Rating in at least the 74th-percentile.

Rountree and Kelley were both bad in spot duty. Rountree was a rookie, but 2021 marks the second year in a row now that Kelley has been a net negative on his carries compared to what his teammates have offered.

So Now What?

Austin Ekeler is great, but he’s also less than 200-pounds. It’s smart from both on-field and financial standpoints to pair him with a pounder that can lessen his load and keep him out of the trenches. Justin Jackson is dynamic, but too small to fill that role. The Chargers have taken shots on guys that fit that mold since losing Melvin Gordon to free agency a couple years ago. But Larry Rountree and Joshua Kelley just ain’t it.

In steps fourth-round rookie Isaiah Spiller. He will likely get a shot at the hypothetical role that the other guys haven’t been able to fill. Many believe Spiller is one of the best backs in this rookie class, both all-around and as a pure runner. I’m less enthused, but it seems likely that he’ll have fantasy utility nonetheless. Especially if Ekeler were to miss any time.

The addition of Spiller probably keeps Rountree and Kelley on the bench. Jackson is currently a free agent. The only other backs under contract for this team are rookies Zander Horvath, Kevin Marks, and Leddie Brown. Horvath might not be a fantasy asset. Though he’s an interesting player as a fullback x running back hybrid with athleticism and pass-catching skills. Brown signed as a UDFA (as did Marks), but he also was a quality three-down back at West Virginia. It wouldn’t shock me to see him make this team.

Final Word

Austin Ekeler has not needed an incredible share of opportunity in this backfield to be an effective fantasy contributor. We should expect him to be productive once again in 2022. His RB7 price tag in dynasty startups (according to DLF) is slightly rich for me. But he’s being appropriately valued in a tier with guys like Joe Mixon, Alvin Kamara, and Nick Chubb.

Outside of Isaiah Spiller, nobody else on this team should have much fantasy value. He’s just inside my top-10 rookie running backs. Mostly on the strength of the quality offensive situation he landed in.

Leddie Brown is vaguely interesting as a very deep dart throw.