Kamren Kinchens
Kamren Kinchens. Image by Samuel Lewis/Icon Sportswire via Getty Images
Kamren Kinchens
Kamren Kinchens. Image by Samuel Lewis/Icon Sportswire via Getty Images

Defensive Back 40 Yard Dash Times: Do They Matter? A Comprehensive Analysis

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In Part 32 of the “Does It Matter?” series, we dove into the question of whether a Defensive Backs’ 40-yard dash time can be a predictor for their NFL success. Here are all our findings:

Methodology

To conduct our analysis, we explored data from the top 50 fantasy football scorers from 2003 onwards, focusing on PPR (Points Per Reception) scoring. Our primary goal was to find whether there is correlation between 40-yard dash times and Fantasy Football success, defined by fantasy football rankings. Within this article, the “bottom 10” term refers to players finishing in 41st-50th place each season.

Why the top 50 players only: we wanted to maintain focus on impactful performances while avoiding fringe roster players who could simply skew results. This top 50 range is a “happy medium” which allows us to compare the best and worst, while allowing us to really compare the best to the worst. Essentially, comparing the top 10 to a number which includes the 11th place finisher does not satisfy our personal itch for finding a trend.

DB 40-Times Averages Chart

The first step of this research involved creating an averages chart. This highlights the trends among the top 5, 10, 11-30th, and 31-50th place finishers since 2003. Upon reviewing this chart, no trends emerged. Surprisingly, in 12 out of 21 seasons (57.1%), the 40-yard dash times for Top 10 finishers were equal to, or even higher, than those for the 31st-50th finishers. This chart usually shows us how the regression testing will end up, therefore, these results led us to begin doubting 40-times as a predictor for DB success. The averages chart can be seen below:

Average Fantasy football DB Results By 40-Times Since 2003
Average Fantasy football DB Results By 40-Times Since 2003

Segmented Top & Bottom 10 Finishers Since 2003

To find deeper insights, we examined the top and bottom 10 fantasy finishers by sorting them according to their 40-times in increments of 0.01 seconds. This segmentation was an attempt to make it more obvious where the higher performances occur at in accordance with 40-times. Contrary to expectations, this analysis showed slower 40-yard dash times occurring more frequently in the top 10 finishers. This shows that faster DB’s were not consistently outperforming their slower peers.

Top 10 NFL Defensive Back 40-Times Since 2003
Top 10 NFL Defensive Back 40-Times Since 2003
Bottom 10 NFL Defensive Back 40-Times Since 2003
Bottom 10 NFL Defensive Back 40-Times Since 2003

DB 40-Times Differences Chart

Our primary goal was to find a sweet spot in Defensive Back 40 yard dash times. To achieve this, we created a differences chart. This chart accounts for each 40-time with the next 0.05-seconds, subtracting the bottom 10 from the top 10. The chart’s desired outcome is a negative number for unique differences (Orange) and a positive number for non-unique differences (Blue). This would indicate the desired consistent top level performances we are hoping for. From this, we found that the range between 4.52 to 4.67 seconds appears to be a top-performing threshold, which we will attempt to verify next.

Comparison of the Top 10 and Bottom 10 DB 40-Times (Plus the next 5 seconds) since 2003
Comparison of the Top 10 and Bottom 10 DB 40-Times (Plus the next 5 seconds) since 2003

Verifying the Optimal DB 40-Time Range: Bottom 10

We now want to backtest this range against historical data from DBs finishing in the bottom 10 since 2003. Out of 136 players, 53 had 40-yard dash times within 4.52 to 4.67 seconds, accounting for 38.2%. This percentage now serves as our baseline to determine whether this range represents an average DB’s 40-time, or a top-performing DB’s 40-time.

Verifying the Optimal DB 40-Time Range: Top 10

To validate this, we looked at the 147 top 10 finishers with a 40-time from 2003 to 2023. We found that 75 of these finishers fell within this same range, accounting for 51.0%. This was a 12.8% increase compared to the baseline, suggesting this 40-time range is possibly the top performing range. Although, we want to slightly alter this to attempt to verify this as the top-producing range, or find a better producing one, which we will do next.

Verifying the Optimal DB 40-Time Range: Fine-Tuning

When we Utilized our spreadsheet for quick adjustments, we discovered that adjusting the range to 4.53 to 4.68 seconds resulted in a 17.7% higher appearance rate among top 10 finishers than in the bottom 10. Therefore, this will be the subject of this study going forward.

Establishing the Critical 40-Time Threshold for Defensive Backs

We further wanted to determine critical 40-yard dash time values for different finishing thresholds. The critical value is simply the threshold at which an outcome change could occur. Here are those findings:

  • Top 10 Max: 4.75 seconds
  • Top 20 Max: 4.75 seconds
  • Top 30 Max: 4.78 seconds
  • Top 40 Max: 4.78 seconds
  • Top 50 Max: 4.78 seconds

Due to this, 4.75 seconds will serve as a critical threshold for when we produce our StarPredictor Score (SPS) model. Essentially, Defensive Backs must run the 40 in under 4.75 seconds in order to not be considered a future bust by our model. We are hoping to have this model fully functional by the beginning of the 2025 NFL season. You can subscribe to our mailing list to get updates on this model when it begins coming out here:

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DB 40-Time Pearson Value

Using standard statistical methods, we analyzed the correlation between a DB’s 40-time and their fantasy production. Here is what prevailed from that:

  • Pearson Value: 0.039

These results indicate no meaningful correlation between 40-times and fantasy performance. Our goal is to reach a Pearson value of >0.1 or < -0.1 when studying world-class athletes as we are. For reference to something that everyone acknowledges matters in prospect scouting, and to show the accompanying Pearson value, RB draft capital prevailed a -0.234 Pearson value.

Decadal Differences

To identify this as an emerging or dying trend, we broke our optimal 40-time threshold down across decades for the top 10 finishers and those ranked 11th to 40th and bottom 10. This chart shows this 40-time range becoming even less significant in the most recent decade. That can be noticed when comparing the Bottom 10 to Top 10 differences in each decade.

2004-2013
Top 1011 through 40Bottom 10
All count6620263
All Between 4.53 and 4.68 seconds388119
% (Optimal Range/all)57.6%40.1%30.2%
2014-2023
Top 1011 through 40Bottom 10
All count7921069
All Between 4.53 and 4.68 seconds418628
% (Optimal Range/all)51.9%41.0%40.6%

Application to 2024 Rookie DB NFL Class

Finally, we evaluated how the 2024 Rookie DB NFL class fits within our optimal 40-time range. We broke it down into players within our optimal range and players outside of it. That breakdown can be seen below:

2024 NFL Rookies in our optimal range (4.53 to 4.68 seconds):
Ryan Watts4.53
Chau Smith-Wade4.54
Josh Proctor4.55
Daijahn Anthony4.55
Kitan Oladapo4.58
Andre Sam4.59
Jaylen Key4.60
Demani Richardson4.60
Evan Williams4.60
Kalen King4.61
Sione Vaki4.62
Isaiah Johnson4.64
Kamren Kinchens4.65
James Williams4.65
2024 NFL Rookies out of our optimal range:
Nate Wiggins4.28
Quinyon Mitchell4.33
Decamerion Richardson4.34
Nehemiah Pritchett4.36
Daequan Hardy4.38
Jarrian Jones4.38
Deantre Prince4.38
Max Melton4.39
Dadrion Taylor-Demerson4.41
D.J. James4.42
Millard Bradford4.42
Kris Abrams-Draine4.44
Elijah Jones4.44
M.J. Devonshire4.45
Cole Bishop4.45
Jaylin Simpson4.45
Marcellas Dial4.46
Willie Drew4.46
Tykee Smith4.46
Dwight McGlothern4.47
Mike Sainristil4.47
Javon Bullard4.47
Andru Phillips4.48
Calen Bullock4.48
Renardo Green4.49
Terrion Arnold4.50
Cam Hart4.50
Khyree Jackson4.50
Myles Harden4.50
Jaylon Carlies4.50
Josh Newton4.51
Ennis Rakestraw Jr.4.51
Dominique Hampton4.51
Tarheeb Still4.52
2024 NFL Rookies with no recorded 40 time:
Jarvis Brownlee Jr.
Caelen Carson
Ryan Cooper Jr
Cooper DeJean
Johnny Dixon
Kamal Hadden
Carlton Johnson
Kamari Lassiter
Kool-Aid McKinstry
Christian Roland-Wallace
T.J. Tampa
Ro Torrence
Josh Wallace
Tyler Nubin
Beau Brade
Jaden Hicks
Patrick McMorris
Malik Mustapha
Tyler Owens

Conclusion

The hypothesis that 40-yard dash times could predict Defensive Backs’ success in the NFL did not find support in our study. Averages and Pearson value analyses suggested that having a faster 40-time is not a guaranteed ticket to a top tier NFL performance.

More Data Next Week!

Our series has always sought to push the boundaries of sports analytics. This latest installment reaffirms our commitment to uncovering the hidden dynamics that define the game. Every Saturday, we’ll dive into intriguing questions, bust myths, and settle debates with thorough analysis. We welcome your input. Therefore, please leave comments or reach out with topics you’re eager to see dissected. All of our research can be found on our Analytics Page. Up next on our agenda for Part 33 of “Does It Matter?” is an examination of Defensive Back RAS (Relative Athletic Score): Does it matter? If so, what’s the RAS threshold necessary for NFL success? Mark your calendars; every Saturday we shed light on the topics that matter to you. All it takes is a quick question being asked and we will go to work for you!

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