September 26, 2020 - by Jason Lisk
Saquon Barkley is out for the season after a knee injury, at age 23 (Photo by Robin Alam/Icon Sportswire)
Christian McCaffrey and Saquon Barkley, the two running backs being drafted in 2020 fantasy football drafts before anyone else, both went down with significant injuries in Week 2. Barkley tore his ACL and is out for the season; McCaffrey has a high ankle sprain that will keep him out for multiple games.
From a betting perspective, how should the Giants and Panthers be valued going forward in games without their star running backs?
In recent years, a large segment of the football analytics community has focused on the idea that “running backs don’t matter,” and it often comes up when running backs are signed to a big contract extension.
Well, let’s dig into the data and examine the historical impact when star running backs miss games.
The first thing we have to do is try to define a star running back, and it’s not easy.
Stats in football don’t just belong to the running back (or quarterback, or wide receiver); they are the result of the interaction of everyone on the field. Nevertheless, better players do tend to put up better stats. With that in mind, our first test was to look at how teams who lost a key running back for most of the season did.
To do this, we looked at all running backs in the last 25 years who fulfilled the following:
We opted to exclude retirements, injuries that pre-dated the regular season, and holdouts, for a few reasons. First, if we are trying to assess situations where a team has to react to a star RB injury during the season, including backs who retired or got injured before the season started introduces more cases where the a team could better plan ahead to address the loss.
Second, some of those injuries would have occurred at the end of the previous season, so rather than trying to decipher when exactly a player was injured, we just excluded RB’s who never played for the team the next season. That leaves us with 24 total cases.
Star RB’s That Got Injured Mid-Season
You can certainly debate the “star” status of some of the backs on that list, and which of them was on a very similar level to Saquon Barkley or Christian McCaffrey today. However, remember that your view of a player may be strongly influenced by how their career finished. Some of the players in the table above were on superstar trajectories before big injuries impacted their careers.
(Put another way, if Saquon Barkley never has another great season after this ACL injury, ten or fifteen years from now young NFL fans will probably be saying “Saquon who?” when you bring him up.)
Now let’s compare the preseason win totals for these 24 teams to the actual win totals they achieved, in these seasons when their star running back had a significant injury.
What we find is that these teams struggled as a group relative to expectations. Compared to the preseason win totals, 6 teams went over, 17 went under, and 1 pushed.
The average preseason win total for these 24 teams was 8.7 expected wins; the actual result was only 6.7 wins.
That might be a clue that the loss of these backs had at least some negative impact on the team’s overall performance.
A closer look, though, introduces some doubt about that hypothesis.
When we separate the data set so that all games with the star RB healthy are included in one bin, and all games with the star RB missing are included in another bin, it doesn’t tell a clear story that these teams collapsed without the star back. (For the purposes of this analysis, we considered a game in which the star RB had the majority of the RB touches for his team as a “star RB healthy” game).
With the majority of these RB injuries, the star running back played in the early part of the season and then missed the latter half. There were exceptions where the back missed some very early games to injury as well, and returned later, but that was not the norm.
Here’s what happened:
So as a group, these teams appear to have been generally underperforming to begin with, and actually did better against the spread with their star RB out or limited. (There could also be another reason for that, which we mention below.)
Overall, the analysis so far has turned up little evidence of a major negative impact when a star running back misses a chunk of games. But we’ve got another angle to explore.
Next, we looked at star backs who missed at least one game during a season and were otherwise productive that year. According to this Pro Football Reference search, there have been 66 player-seasons since 1995 where a running back who averaged 15.0 or more fantasy points per game (1 point for every 10 yards and 6 points for every touchdown) missed at least one full game that year.
We excluded all seasons where a back missed only a Week 17 game, which is usually the result of a team resting starters.
For the other games, we looked at the results for the very first game that the star RB missed due to injury that season. Here they are:
So, a big shrug of the shoulders there. However, we also see quite a divergence in performance if you cut the data into bins of older vs. more recent seasons:
(For reference, only two cases that qualified last season. Tennessee, having just lost Derrick Henry, lost to New Orleans by 10 as a 3.5-point underdog. Minnesota, having just lost Dalvin Cook, lost to Green Bay by 13 as a 4-point favorite. Both were ATS losses.)
Are More Efficient Betting Markets Having An Impact?
With such a small sample size of data, that time-based performance split could largely be the result of randomness doing its thing. It’s such a stark change that it’s hard to believe that anything fundamental changed so quickly.
Still, if the movers and shakers of the betting markets increasingly have been concluding that RB’s don’t matter as much as conventional wisdom implied, it stands to reason that you can no longer get as good of a betting line on a team that just lost its star RB than you could get 10 or 15 years ago. And in theory, that sort of adjustment would have contributed to worse ATS performance by these teams in recent years.
At the same time, a 3-14-1 ATS record since 2010 would seem to imply that the market has overcorrected for the presumed lower-than-previously-believed value of star RB’s in recent years. With just 18 of these games to go on, it is what it is, and all you can do is theorize.
The evidence that teams struggle without star backs is mixed. Overall, it doesn’t look like teams who had significant RB injuries saw sudden and major downturns in their performance levels. In the short term, there is some data suggesting that recent teams have struggled against the spread in the first game missed by a key back, but it could just be random.
Taking a step back, though, why might the running back injury impact not be as high on things like season winning percentage as most people might think? It’s not likely that teams are misjudging who the most talented running backs are.
A potential confounding factor is that in today’s NFL, passing tends to produce higher expected points and increase win probability more than rushing. If a team leans very heavily on a talented running back just because he happens to be on the roster, that team may actually be behaving sub-optimally in terms of overall offensive strategy and play calling.
Of course, this is just a theory put forth by some stat geeks who have never actually played or coached NFL football. But at the very least, it’s interesting to wonder if, for some teams at least, losing their option to use a very talented RB actually led them to start to make better decisions in terms of pass/run splits, and those better decisions helped cancel out the loss of a star player.
So as you assess the potential betting impact of a team losing a star RB, you should consider not only the individual vs. replacement talent, but also whether it could lead the team to adapt a more pass-heavy offense, and what its capabilities are in that area.
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