Fantasy Football Deep Dive: Correlation + Stability Of Key Metrics

There may be no more difficult task in sports than projecting a player’s statistical output. While fantasy analysts should feel confident in their rankings, the fact of the matter is that there is so much variance within each game, that statistics tend to fluctuate on a yearly basis.

However, this doesn’t mean we shouldn’t try our best to formulate ideal expectations on the value each player could provide to one’s fantasy team. There are several available statistics available for public use, but the question remains: which statistics are the most important?

To answer this question, I believe there are two aspects of a statistic that should be measured: its year-to-year stability and its correlation with projecting statistics that lead specifically to fantasy points scored. With the help of data scientist Ajay Patel, we will be looking at several statistics for each position group in fantasy football, analyzing their stability and correlation when it comes to projecting yards and touchdowns. With this information, my hope is that we can better understand what to look at when positional and overall rankings, which will always us to have the most optimal drafting and roster construction strategy.

What statistics are the most meaningful? How can we use this to gain an edge over our peers? Let us dive deep into the data!

Quarterbacks

Stability of Key Statistics (Passing)

Pro Football Focus does a fantastic job grading players in a way that separates process from the actual results, so it isn’t a surprise that their overall passing grade shows up as the most stable statistic for quarterback play. Meanwhile, average depth of target and overall pass attempts are process-based statistics, so they generally should have a higher overall stability. When looking more at results-oriented metrics, it appears that accuracy is the most stable on a year-to-year basis, but I’m surprised that interceptions were more stable than turnover-worthy plays; turnover-worthy plays are meant to describe how many turnovers a quarterback should have committed. Still, the difference there is negligible, and what really should be focused on is the lack of correlation with touchdown rate. Not only is touchdown rate dependent on the success of an offense, but also on what the team does once in a position to score. There are too many moving parts to rely quarterbacks consistently benefitting from strong touchdown luck consistently, meaning it should definitely be de-emphasized compared to other efficiency metrics.

With that addressed, let’s see how statistics from the past season fare when projecting the statistics that correlate directly with fantasy points for the following season:

Correlation With Projection Yards/Attempt

#1. Previous Yards/Attempt

#2: PFF Passing Grade

#3: Adjusted Completion%

#4: Big-Time Throw Rate

Although yards/attempt is dependent on outside circumstances, there is a reason that the quarterback is considered to be the most important position in football; their quality of play is the best predictor of the quality of an offense. Plus, unless there is extreme turnover, it’s likely that a quarterback will continue to benefit from outside circumstances, such as offensive scheme and strong receiving talent, so it makes sense that previous yards/attempt is the best predictor of future yards/attempt. That said, since those circumstances do change, it is important to also look at efficiency metrics that a quarterback has more power over. That’s where grading their process and looking at their accuracy comes into play, and when a situation changes (new team, different offensive scheme), I would find these metrics to be even more significant.

Projecting Touchdowns

1. PFF Passing Grade

2. Big-Time Throw Rate%

3. Yards/Attempt

4. Previous Touchdown%

5. Adjusted Completion%

As you can see, touchdown% has very little predictive power on future results. For this reason, fantasy players can gain an edge by looking at quarterbacks who either benefitted or suffered from touchdown luck. Aaron Rodgers, for instance, likely won’t sustain the touchdown success he had last year, while someone like Joe Burrow might be in line to benefit from better luck. In general, it is becoming clear that looking at efficiency metrics and analyzing opportunity, rather than banking on touchdowns, is a much more optimal strategy.

Projecting Interceptions

1. Previous Interception%

2. Average Depth of Target

3. Turnover-Worthy Play Rate

4. Yards/Attempt

In addition to looking at previous interceptions, understanding that quarterbacks who throw the ball down the field are likely to throw more interceptions is important to understand. For some quarterbacks, this extra risk is worth it, as their success on vertical concepts can lead to overall fantasy success and a lot of 20+ yard passes. For less-accurate quarterbacks such as Drew Lock or Carson Wentz, however, there might not be enough high-end play to compensate for the mistakes made with that play style.

Stability of Statistics (Rushing)

For quarterbacks, their success running the football tends to be much more stable than their success passing. Why would this be the case? My guess is that rushing success is less reliant on other circumstances. For quarterbacks such as Lamar Jackson and Kyler Murray, this is critical, and a major reason why they’re considered top-five fantasy quarterbacks. Additionally, when it comes to projecting yards/attempt and touchdown rate, looking at their success in those metrics previously is the best forecasting method, based on the research conducted.

Running Backs

Stability of Statistics

There is a lot to break down here. Let’s start with a running back’s rushing success. Being able to force missed tackles is easily the most stable statistic, as it is a skill that is not reliant on the offensive line. Furthermore, touchdown rate is more stable than with quarterbacks, as certain prototypes of running backs are likely to specialize more in those short yardage situations. I’d make sure to look at which running backs benefitted/were hurt from fumbles. Actually losing a fumble is something that is certainly not a skill but a subject of luck, so outliers in terms of fumble luck are likely to not be represented properly by previous fantasy points/game.

As for receiving ability, actual production is actually more stable than their receiving grade. Why would this be the case? The amount of receiving opportunities each running back gets is widely spread, and yards/route run is able to factor that in more; running backs with more targets and receptions, stable metrics, are able to be more efficient per route run. In other words, it’s less impressive to earn a strong receiving grade when you have five receptions as opposed to sixty, so relying on actual receiving production is critical.

What should fantasy owners prioritize more: rushing prowess or receiving ability? In my opinion, it’s a clear balance, as neither is more stable than the other. Rather, given that running back success isn’t super consistent, I’d want to have a running back who has as many avenues to contribute as possible in order to minimize the overall risk associated with the player.

Projecting Rushing Yards/Attempt

  • Previous Yards/Attempt, PFF Rushing Grade, Yards After Contact/Attempt All Equally Important

Since rushing success is so predicate on a running back’s offensive line and an opposing defense’s box count, it’s important to look at factors that are more in their control. That’s where rushing grade, which separates other factors from running back quality, in addition to yards after contact/attempt, come into play. By analyzing the running back first outside of their situation, we can get a better idea on how efficient they will be.

Projecting Touchdowns

1. PFF Rushing Grade

2. Yards/Attempt and Yards After Contact/Attempt

3. Previous Touchdown%

Although running back touchdowns are more stable than touchdowns for quarterbacks, it is still dependent on overall team quality- you need to have enough opportunities in the red zone to score touchdowns consistently. For this reason, expecting that, over time, the best running backs will score the most touchdowns, while factoring in the projected quality of the offense, is the best way to estimate production in this area.

Projecting Running Back Yards/Route Run

1. Previous Yards/Route Run

2. Average Depth of Target

3. PFF Receiving Grade

As mentioned, looking at previous running back production, with how stable receptions are, is a great way to protect future receiving success. Additionally, the farther a running back’s targets are from the line of scrimmage, the less reliant they are on a high target share. Thus, average depth of target is very important; finding running backs who are used as actual receivers, rather than just on traditional screens, is also a viable strategy.

Projecting Running Back Receiving Touchdowns

1. Average Depth of Target

2. PFF Receiving Grade, Yards/Route Run

3. Targets, Receptions

This is surprising, but I can understand why average depth of target is the best predictor of future receiving touchdowns. If passes of greater distances are more likely to lead to explosive plays, could it be that the most stable way a running back scores touchdowns as a receiver is through receptions of greater yardage? In the red zone, running back rushes or passes to bigger-body receivers tend to occur more often, which is why opportunities may matter less than the quality of those opportunities.

Wide Receivers/Tight Ends

Stability of Statistics

As opposed to running backs, the production of wide receivers and tight end is much more stable. Quarterbacks see general fluctuation in their average depth of target based on state of the game and the offensive scheme they’re in, but wide receivers are generally asked to run similar route patterns to what they’re used for. We’ve seen players like Robby Anderson be utilized differently upon changing teams, but consider him the exception to the rule. Since better wide receivers tend to get open more, high-volume receivers do tend to continue to produce volume. Where you can look to find value at the receiver and tight end positions is those who struggled with drops, touchdowns, or poor contested-catch luck. These are much more volatile facets of play, and although players like Kenny Golladay have demonstrated a certain prowess when it comes to contested catches, I’d need a much larger sample size to feel confident in someone thriving in a similar role.

Projecting Yards/Route Run:

1. Previous Yards/Route Run

2. PFF Receiving Grade

3. Receptions

4. Targets

5. Yards/Reception

6. Average Depth of Target

With receiving production being much more consistently on a yearly basis, it isn’t a surprise that the best way to project one’s yards/route run is to simply look at their prior success in that metric. What I find most interesting, however, is that volume seems to have slightly greater power when it comes to projecting future production than efficiency. Players with a higher average depth of target tend to be much more volatile, and thus might be more useful in best ball formats than weekly leagues. Now, vertical threats are a safer bet than those than specialize after the catch, but quantity ultimately trumps quality.

Projecting Touchdowns/Route Run:

1. PFF Receiving Grade

2. Targets

3. Receptions

4. Previous Touchdowns/Route Run

Once again, it’s clear that we need to not pay too much attention to previous touchdown production. Rather, expect quality receivers, and, more specifically, quality receivers with an adequate amount of opportunities, to score the most touchdowns.

Overview

So, what should we take away from this?

For quarterbacks, I’d balance volume with efficiency. However, with how much more stable rushing production it is, I’d certainly want to target. Running backs, meanwhile, see such fluctuations with their efficiency, so I’d want to a) target someone guaranteed to get a lot of opportunities and b) those who can contribute as both a runner and receiver. This minimizes the risk accosted with the players, which is critical at such a premium fantasy position.

What about wide receivers and tight ends? I’d focus first on their projected volume, but, unlike running back, the quality of the receiver matters significantly. You’d rather have an efficient second option in an offense than someone projected to lead a team in target share but with severe questions about his overall talent level.

Dismissing previous touchdown success, paying key attention to volume, and relying on stable metrics is paramount when it comes to building the best fantasy team possible. At the end of the day, process may not always lead to the results; this is what happens with a sport that is subject to an extensive amount of variance. However, all we can control is our process. Over time, this should lead you to the top of your leagues!

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