The Fantasy Mythbusters: Is There a Rookie Bump?

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In the Fantasy Mythbusters series, we set out to test some of the standard assumptions shared across the fantasy landscape. One common ‘tip’ is to target rookies – especially WRs – in the second half of the year. The logic is solid: the NFL represents a new level of speed and physicality compared to college, and it can take players time to adapt to both the more advanced environment and the new playbook. However, it’s possible that this assumption is colored by some standout examples. Everyone remembers Justin Jefferson getting off to a slow start before posting the greatest rookie wideout season ever; we could, therefore, be swayed by the availability bias of notable examples.

Either way, this is a timely question: we just finished Week 8, which is just about the halfway point of the fantasy season. We’ve had some monster rookie performances in 2021, most notably Ja’Marr Chase and Najee Harris, both weekly must-starts at their respective positions. However, we’ve had our fair share of disappointments: most rookie quarterbacks, for example, have had a difficult ‘adjustment period’. WRs Devonta Smith and Jaylen Waddle have flashed, but with limited upside and consistency (thanks in part to the struggles of their respective teams). Should you be targeting some of these rookies who haven’t performed up to expectations?

To get to the bottom of things we turn, as always, to the data (from nflfastR). We’ll be looking at players that played in 9 games or more and scored 100+ points in a season since 2010. All scoring is in the Half PPR format.

Rookies vs. Veterans

We can start by comparing the performance of rookies vs. veterans (defined here as any player that is not a rookie). These density charts show the rookie distribution in yellow and the veteran distribution in blue. We’ll start by looking at the first half of the year, or Weeks 1 – 8:

It’s clear that rookies are, generally, worse than veterans! The veterans have a fatter ‘right tail’ (boom weeks), while the rookies have more density on the left side (bust weeks). This is especially pronounced for QBs, which makes sense: learning to run an offense during your first year in the league can be quite daunting, and we’ve seen some extreme examples of that this year (especially with Justin Fields in Chicago).

The TE chart is also interesting: rookies have the highest ‘density peak’ of any player. This is basically saying that the distribution of rookie tight ends is very narrow, with limited upside, and is centered around a low value (about 7 PPG). This gels with the conventional wisdom that tight ends take time to really ‘break out’. Also, we can see the right-skew inherent to the RB charts compared to the other positions, which reinforces why it is the most important position in fantasy.

Let’s consider these same charts, but for the second half of the year (Week 9 on):

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This is an interesting change: the yellow rookie mound has crept up on the blue veteran mound compared to the previous chart. In most, cases, the veterans are still slightly better, but it looks like rookie RBs might have a razor-thin edge on the veterans. There might be something to this myth, so let’s forge on…

Rookie Improvement

The above charts are interesting, but we want to be comparing first-half rookies vs. second-half rookies, not rookies vs. vets. We can do that with the chart below; the blue mound is first half rookies, the red mound second half rookies. Remember, these are the distributions since 2010:

The results are in: for QBs, WRs and RBs (especially RBs) it looks like there is real improvement in the second half of the year! TEs are a strange case: the second half of the year looks more boom-bust than the first, which could imply that either TEs start to emerge or fall out of favor. Let’s look at the actual breakdown of average PPG across the season; to get a bit more nuance, we can also consider a reasonable ‘ceiling’ (75th percentile) and ‘floor’ (25th percentile) change:

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  • The PPG increase is consequential: about 1.0 PPG for QBs and WRs, and nearly 2.5 PPG for RBs. These are large differences. Scoring 1.0 PPG more (and especially 2.5 PPG more) can move you up the positional rankings significantly. TEs are flat-to-down, which makes sense, since the position breaks out later than RBs and WRs on average.
  • RBs and WRs both see a similar increase in floor and ceiling. QBs, interestingly, don’t see much of a change in ceiling, but have a much higher floor in the second half of the year. This can be seen in the density plots above, and it makes sense: while a rookie QB might not necessarily set the world on fire, he will stop making (as many) costly mistakes that lead to terrible fantasy outings in the second half of the year.
Trends

Now that we’ve seen some pretty conclusive data, let’s look at some interesting trends in this so-called ‘Rookie Bump’. To start, we can see how the ‘bump’ (increase in expected PPG from the first half of the year to the second half) has changed over time:

  • The QB bump has gotten, generally, larger over time. My guess is that this is due to the added upside at the position in recent years thanks to increasingly mobile QBs; we know that quarterbacks that can run the ball are extremely valuable for fantasy. On the flip side, the RB bump, which is the largest of the positions (and was never once negative in this sample) has been narrowing. In this case, the deterioration is likely due to the increased rate of the ‘RB by committee’ approach in recent years, which naturally caps the upside of individual backs.
  • The wideout bump has been relatively constant and consistently positive. The TE chart is funny: one single point sticks out in 2010 as a large rookie bump, while the rest are close to zero or negative. This 2010 point is likely swayed by Rob Gronkowski, who caught seven TDs in the second half of his rookie year (including a 3-touchdown performance in Week 9).

Another natural question is to consider if these rookie improvements are coming from rookies actually getting better, or just being used more as coaches work them into the game plan. We can look at rushing and receiving averages for RBs and WRs to answer this question. These statistics are on a per-game basis:

As these tables make clear, the improvement is largely from volume, not efficiency. If you estimate yards per carry or reception with these charts, you will see they are the relatively the same through the first and second half. It’s the attempts and targets – the player usage – that rise over the course of a season and lead to more fantasy points. We do see YAC increase for WR, and one can make the argument that skill is the most important determinant of targets, so growing ability does play a role in the higher point averages.  Note that WRs do catch about .04 more TDs in the second half; this table just goes to one place after the decimal.

Finally, it is useful to make sure that this ‘second half effect’ applies to just rookies and not veterans as well. We can recreate the same PPG chart with vets to confirm that there isn’t as much change between the first half of the year to the second; if anything, performance declines a bit over the back half of the season.

Myth…

CONFIRMED. For QBs and WRs, we see about a 1.0 PPG increase in the second half of the year; for RBs, this number is about a whopping 2.5 PPG. QBs see a bump in their floor, while RBs and WRs improve in both floor and ceiling; in addition, these players are generally seeing gains from increased volume as opposed to rapidly growing skills.

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The implication is clear: it’s time to target rookies in your fantasy leagues. There are a ton of options at QB – Trevor Lawrence, Zach Wilson, Mac Jones, Justin Fields, Trey Lance – that project to cut down on ‘rookie mistakes’ and deliver more solid fantasy performance. Some exciting WRs – Jaylen Waddle, Devonta Smith, Rondale Moore – could be worked more into the gameplan and see more viability as a result. One RB that I’m targeting heavily is Michael Carter coming off of his big week; we saw how the ‘back-half’ effect is most prominent for running backs.

Although the TE position is strange, we did see the scoring distribution between to separate – into boom and bust – over the back half of the season. That’s good news for Kyle Pitts, by far the most fantasy relevant rookie tight end, who has been seeing an increased workload and is hopefully due for many more ‘boom’ weeks.

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Did I miss anything? Is there another myth you’d like to check out? Message me on Twitter.

*This is an estimation, it won’t be exactly the average yards per carry or reception

Comments

Matt DiSorbo says:

Thanks to you both for reading!

Matt says:

Matt’s crushing it. Cool article

Joe Davey says:

Woah! This is great.

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