Does Sophomore Slump Exist in the NFL?

By Matty Cheng, Ella Papanek, Alexander Kim, Jamie Menhall, Thomas Jaklitsch, Paul Marino, Edward Zhao, and Frank Zhu

This season the hyped Cleveland Browns have failed to meet expectations, starting with their quarterback Baker Mayfield who, last year, broke the rookie record in passing touchdowns, but has seen drops in nearly all significant statistics in his second year, including decreases in his completion percentage, yards per attempt, and touchdown rate along with an increase in his interception rate.  When a second year player sees a decrease in performance, sometimes people explain it as a “sophomore slump” – an idea that players generally see performance decline in their second year.  

Beyond Baker Mayfield, we have seen this in another notable name in RGIII who was Offensive Rookie of the Year and had the 7th best QBR (69.4 – the best mark for a rookie in NFL history) in 2012, but fell to 23rd best in the league for his sophomore campaign at a QBR of 51.8.  RGIII’s case could plausibly be explained by his injury in the playoffs of his rookie year, which may have lessened speed and agility, making him less effective as a dual threat in his second season. Not needing to fear his running ability, opposing defenses could drop more players into coverage, leading to more interceptions and less efficiency through the air.  

Yet another example of a sophomore slump is in Dak Prescott.  He threw many more interceptions, jumping from only 4 in his Pro Bowl rookie year to 13 in his sophomore year. In his rookie year, he posted an adjusted yards gained per pass attempt of 8.6, which was third in the entire league behind only MVP Matt Ryan and Tom Brady.  In his second year, Dak declined to 6.5 AY/A, 21st among quarterbacks. In other words, he contributed 25% less yardage per throw in comparison to his rookie year.

On the other hand, we have also seen cases such as Lamar Jackson this year and Adrian Peterson who had an outstanding rookie season who went on to have an even better sophomore year.  He rushed for 1341 yards on 238 carries for a very impressive 5.6 yards per carry, and was rewarded by a Pro Bowl selection as well as being awarded Offensive Rookie of the Year. He then actually improved in his second year by leading the league in rushing yards with 1760 yards on 363 carries for 4.8 yards a carry, making him only the fifth player in history to reach 3,000 yards in his first two seasons.

With some conflicting cases about possible sophomore slump, we examined the existence of sophomore slump and if perhaps the existence differs by position. Given that the sophomore slump narrative is typically applied to players who overperformed in their rookie year, we focused on players who had above average rookie seasons. We only examined that players had played in at least 10 games in both their first and second season.  This method reduces the effects of injuries, small sample size, etc. Ideally, we attain a balance between confidence in the accuracy of player statistics and a minimal level of restriction (to allow for a sufficiently large sample).  

For quarterbacks, the performance statistic we examined was QBR.  QBR is a statistic created by ESPN that incorporates all of a quarterback’s contributions to winning, including passing, rushing, turnovers, and penalties.  For all other position groups (do not have QBR), we used Pro Football Focus’ Player Grade, which incorporates a range of advanced statistics and is made from Pro Football Focus’ staff charting and grading every player on every play in every game. 

The figure below charts the performance of quarterbacks across their careers:

We can see from the green line (quarterbacks who perform better than average in their first year) that there is indeed a sophomore slump. From year one to year two, we see a decline of 12.1% in QBR and this found to be statistically significant by running a paired t-test that compares each player’s performance in his first and second year.  We also observe that this sophomore slump from the high performing rookies goes against the natural average trend of quarterbacks that improve performance from their first to second year as seen by the red line (represents all quarterbacks). In addition, these quarterbacks see a slight rebound in performance in year three, fitting true idea of a “slump.” It is interesting to note that the quarterbacks represented in the green line consistently on average perform better than other quarterbacks for every single year in their career (except for year ten), while we only selected this group by their first year performance, meaning that first year performance is very indicative of (relative) career performance.  


Next, we examined other offensive players: running backs, wide receivers, and tight ends.  

As seen in the graphs above, we once again observe a decrease in performance from the first to second year for those who performed above average in their rookie season.  Running backs, wide receivers, and tight ends saw their performance (measured by PFF grade) decrease by 5.6%, 3.1%, and 6.1% respectively, all statistically significant. Despite the case of Adrian Peterson, running backs overall do show a sophomore slump.  Like the quarterbacks, the natural trend of these positions groups was to show an improvement in performance for their second year, but these high performing rookies slumped against the trend. While the tight ends matched the quarterbacks in rebound performance for their third year, the running backs and wide receivers actually saw a further decline in performance for their third year.  

We did the same analysis for the defensive positions of cornerbacks and safeties, shown below:

We observe sophomore slump for these positions as well, seeing cornerback and safety performance and decrease by 8.2% and 9.4% respectively, both statistically significant. Unlike the other positions, the trend for these rookies overall (not just the outperforming rookies)  was actually to have a decline in performance in their second year.

In conclusion, rookies across many offensive and defensive positions that perform above average in their rookie seasons tend to show a decline in performance on average (between 3-12% across positions) in their second season.  However, most display a rebound performance in subsequent years.

If you have any questions for Matty about this article, please feel free to reach out to him at chengm@college.harvard.edu

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