Connect with us

Bears

Stat Breakdown: Justin Fields and the Average Rookie QB

How Justin Fields ranks and compares to the average rookie QB and which stat categories are most correlative to future success.

After reading through Johnathan Wood’s analysis of Justin Fields’ rookie season, I was inspired to dig into some data myself. Therefore, I decided to inspect a few statistical categories for the Chicago Bears‘ young passer and compare them against the average rookie QB. This piece will not cover the same depth of concepts as Johnathan Wood’s articles did, as it is more geared toward rookie passers. I highly suggest any Bears fan go read his Fields articles.

Rookie QB Data

I decided to look at the following passing specific situations (per PFF):

  • Deep Passing (pass attempts traveling 20+ yards beyond the LOS through the air)
  • Intermediate Passing (pass attempts traveling 10-20 yards beyond the LOS through the air)
  • Short Passing (pass attempts traveling 0-9 yards beyond the LOS through the air)
  • Passing Behind the Line of Scrimmage (LOS)
  • Clean Pocket Passing
  • Pressured Passing

I want to point out that because all this data is for pass attempts, it does not include any adjustment for rushing prowess or success. Within each situation, I looked at these stats, where relevant:

  • Adjusted Completion %: Adjusts for drops, throwaways, spikes, passes batted at the LOS, and passes thrown as the QB was being hit.
  • Big Time Throw Rate: A throw into a tight window that requires excellent timing and accuracy on a high-value offensive play.
  • Turnover-Worthy Play Rate: Fumbles in the pocket, throws that are interceptable, and interceptions. 
  • Average Depth of Target: The passer’s average air yards beyond the LOS per pass attempt.

Additionally, I set the QB drop-back limit for each rookie passer at roughly 350. Justin Fields dropped back to pass 353 times in his rookie season. Therefore, I matched that number as closely as possible for each QB. The PFF data for rookie QBs goes back to the 2009 season. Therefore, I included every rookie QB to drop back at least 300 times since 2009. The dataset includes 45 rookie passers.

Rookie QBs by Passing Depth

Throwing Deep (20+ Air Yards Beyond LOS)

Rookie QB Deep Passing
Rookie QB Deep Passing Ranks through ~350 dropbacks

Justin Fields ranks as the fifth-best deep passer within the dataset, and the best among 2021 rookies. He threw deep the fourth most often (15.9%), with the 19th ranked adjusted completion percentage (44.2%). Moreover, Fields recorded the best big-time throw rate (34.8%) of any passer in the dataset. However, his ranking of 23rd for turnover-worthy play rate (8.7%) is not as sharp.

The average QB in the dataset threw deep 12% of the time. Among QBs who threw deep more than 12% of the time, the average adjusted completion rate was 40.8%. Within that same group, the average big-time throw rate was 22.8%, and the average turnover-worthy play rate was 9.6%.

Therefore, Justin Fields was above average in his deep accuracy, well above average in big-time throws, and about a little better than average at avoiding risk. Fields has special deep-ball ability, and these numbers are just one way to confirm that.

Throwing Intermediate (10-20 Air Yards Beyond LOS)

Justin Fields Bears Rookie QB stats
Rookie QB Intermediate Passing Ranks through ~350 dropbacks

Justin Fields ranks as the 11th-best intermediate passer within the dataset, and the best among 2021 rookies. He threw to the intermediate the 12th most often (24.1%), with the 21st ranked adjusted completion percentage (58.5%). Surprisingly, Fields’ big-time throw rate to the intermediate does not match his deep passing numbers. He ranked 35th in big-time throw rate (2.7%). However, his ranking for turnover-worthy play rate significantly improved in this range. He did not have a single turnover-worthy play when targeting the intermediate, ranking first.

The average QB in the dataset threw to the intermediate 21.7% of the time. Among QBs who threw to the intermediate more than 21.7% of the time, the average adjusted completion rate was 60.6%. Within that same group, the average big-time throw rate was 6.7%, and the average turnover-worthy play rate was 7.1%.

Therefore, Justin Fields was slightly below average in his intermediate accuracy, well below average in big-time throws, and well above average at avoiding risk. It feels like he must have been very risk-averse in this part of the field, only throwing to it when players were wide open. That would explain the lack of big-time throws and turnover-worthy plays.

Throwing Short (0-9 Air Yards Beyond LOS)

Rookie QB Short Passing
Rookie QB Short Passing Ranks through ~350 dropbacks

Justin Fields ranks as the 25th-best short passer within the dataset and the worst among 2021 rookies. Because big-time throws are rare at short throw depths, big-time throws were not included in the ranking.

Fields threw to the short portion of the field the 17th most often (47%), with the 32nd ranked adjusted completion percentage (74.8%). Additionally, he ranked 22nd in turnover-worthy play rate (2.2%). The average QB in the dataset threw to the short portion of the field 44.9% of the time.

Among QBs who threw short more than 44.9% of the time, the average adjusted completion rate was 78.3%. Within that same group, the average turnover-worthy play rate was 2.2%. Therefore, Justin Fields was below average with his short accuracy and average at avoiding risk. The accuracy here is concerning and could speak to his ability to make pre-snap reads and follow up with adjustments post-snap. The quick game is not Fields’ strength and is something that he needs to continue to work on. 

Throwing Behind the LOS

Rookie QB Passing Behind the Line of Scrimmage (LOS)
Rookie QB Passing Ranks behind the LOS through ~350 dropbacks

Justin Fields ranks 44th for throwing behind the LOS, and the worst among 2021 rookies. Because big-time throws are almost non-existent behind the LOS, big-time throws were not included in the ranking.

Fields threw behind the LOS the third least of any QB in the dataset (8.1%), with the 32nd ranked adjusted completion percentage (90.9%). Additionally, he ranked 45th in turnover worthy play rate (4.2%). The average QB in the dataset threw behind the LOS 13.6% of the time.

Among QBs who threw to behind the LOS less than 13.6% of the time, the average adjusted completion rate was 91.2%. Within that same group, the average turnover-worthy play rate was 1.2%. Therefore, Justin Fields was average with his accuracy behind the LOS and well below average at avoiding risk. The risky plays here are a major concern. Whether you want to chalk it up to Matt Nagy’s offense or not, that number stands out.

Although, I need to temper this with some mention of sample size. Because Fields only threw 22 passes behind the LOS, his one turnover-worthy play is shown at a rate of 4.2%. He had the same amount of turnover-worthy plays behind the LOS as every QB above 0%. But because he rarely threw short of the LOS, the rate is boosted.

Rookie QBs by Pressure Circumstances

Kept Clean

Rookie QB Passing Kept CLean
Rookie QB Passing Ranks when Kept Clean through ~350 dropbacks

Justin Fields ranks as the sixth-best passer when kept clean, and the second-best among 2021 rookies (after Mac Jones). Despite ranking well overall, he had the 37th ranked adjusted completion percentage (70.9%). While that brings his rank down, his depth of the target, big-time throws, and risky plays pull it back up. But why is the depth of target included in the rank here? Because I want a QB that looks to hit home runs when he is in a clean pocket. Dropbacks under pressure are extremely variable and outcomes are inconsistent. This is why I value a QB who stays aggressive in clean situations and can deliver without putting the ball at risk.

Fields recorded the 11th largest average depth of target (9.0). On top of that, he had the sixth-best big-time throw rate (6.5%). But the cherry on top here is that he had the third-best turnover-worthy play rate (1.4%).

The average QB in the dataset had an average depth of target from a clean pocket of 8.15. Among QBs with an ADOT over 8.15, the average adjusted completion rate was 73.9%. Within that same group, the average big-time throw rate was 4.7%, and the average turnover-worthy play rate was 3.8%.

Therefore, while Justin Fields was below average in accuracy from a clean pocket, he was above average in big-time throws, and well above average at avoiding risk. When you calculate big-time throw rate over turnover-worthy play rate, only two rookie passers have been better from a clean pocket since 2009: Russell Wilson and Matt Ryan.

Under Pressure

Rookie QB Passing Under Pressure
Rookie QB Passing Ranks Under Pressure through ~350 dropbacks

Justin Fields ranks as the 19th-best passer when under pressure, and the second-best among 2021 rookies (after Trevor Lawrence). He had the 32nd ranked adjusted completion percentage (57.7%). However, Fields recorded the fourth largest average depth of target (12.7), meaning that he was throwing to more difficult depths of the field. Unfortunately, the more difficult throws could not bail him out here, as he ranked 19th in big-time throw rate (5.3%) and 35th in turnover-worthy play rate (6.9%).

The average QB in the dataset had an average depth of target when pressured of 10.7. Among QBs with an ADOT over 10.7, the average adjusted completion rate was 58.8%. Within that same group, the average big-time throw rate was 5.6%, and the average turnover-worthy play rate was 6.0%.

Therefore, among the more aggressive passers when pressured, Fields was slightly below average in accuracy. Additionally, he was slightly below average in both big-time throw rate and turnover-worthy play rate. This may be a sign that Fields needs to learn to take what is there in the face of pressure. The data paints a picture of a QB who is trying to do too much when faced with tough situations.

Justin Fields Ranks and Correlation to Long-Term Success

Rookie QB Stats vs Career Success
Correlating Rookie QB Stats to Career EPA/Play

So, what does this all mean? How can we take this data and try to turn it into an all-telling crystal ball? Well, we cannot. But we can try to use this data to create a baseline for how similarly ranking QBs have turned out.

As the chart tells us, deep passing success as a rookie has a very weak correlation to long-term NFL success. Because the deep pass might only happen a few times a game, it cannot be the basis for what a QB does. Unfortunately for Justin Fields and Bears fans, deep passing is not a crystal ball by any means.

Similarly, short passing, passing behind the LOS, and passing under pressure are only weakly correlated to future NFL success. That is good news for Justin Fields and Bears fans, as it means that this is an area that many QBs get better with time. While these might show a little bit of correlation, they are not crystal balls either.

That brings us to the two areas that are correlative to future success. Those being passing to the intermediate part of the field and passing from a clean pocket. These are the two areas that might be crystal balls in some capacity.

Rookie QB Intermediate vs Career EPA
Rookie QBs Intermediate Passing Ranks vs. Career EPA/Play

Passing to the intermediate returns a correlation coefficient of 0.44, which represents a correlative factor (not to be confused with a strong correlation). QBs who rank in the top half for intermediate-depth passing average EPA/Play of 0.058. The QBs ranking in the bottom half average -0.021 EPA/Play.

Rookie QBs Kept Clean vs career EPA
Rookie QBs No Pressure Passing Ranks vs Career EPA/Play

Passing from a clean pocket returns a correlation coefficient of 0.55, which represents a correlative factor (not to be confused with a strong correlation). QBs who rank in the top half of rookie passers from a clean pocket average EPA/Play of 0.079. The QBs ranking in the bottom half average -0.041 EPA/Play.

Justin Fields Rookie Season Review

In review, among 45 rookie QBs since 2009 through their first ~350 dropbacks, Justin Fields ranks as follows:

  • Deep Passing: 5th
  • Intermediate Passing: 11th
  • Short: 25th
  • Behind the LOS: 44th
  • Kept Clean: 6th
  • Under Pressure: 19th

The most telling areas are intermediate passing and passing when kept clean. Fields ranks 11th and sixth in these two areas, respectively. That bodes well for his future. However, Fields will NEED to improve his short passing and passing behind the LOS and prove that his deep passing success was more about talent than luck. I believe that his deep ball will stand the test of time, but it is impossible to be sure.

Follow On Tap Sports Net on social media!

Sign up to receive awesome content like this right in your inbox, from On Tap Sports Net.

We don’t spam! Read our privacy policy for more info.

I like spreadsheets and football. I aim to take an analytical approach to my football research while also realizing the physical nature of football and how that impacts the numbers. While my main focus is Chicago Bears, I also write about the NFL as a whole.

Click to comment
Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Inline Feedbacks
View all comments

Listen To Bears On Tap Podcast

BET WITH BETRIVERS ILLINOIS

Advertisement Beer and Bourbon Box 300x250

More in Bears