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Navigating Bear Markets: How Soon is Too Soon to Start a Rookie QB?

How long will Andy Dalton last as the Bears’ starting QB with Justin Fields behind him? History tells us not long.

Justin Fields Chicago Bears
Photo: ClutchPoints

How soon is too soon to start a rookie quarterback? This is a question that is on all of our minds, as Bears fans are looking forward to seeing Justin Fields donning the navy and orange. I turned to the numbers to see if we could draw anything based on the past.

Chicago Bears 2021 NFL Draft
Photo: Mfa1O52/Twitter

Methodology

I accumulated the college games started, college pass attempts, NFL ANY/A+, and NFL EPA/Play for every QB drafted in the first round between 2004 and 2018. I limited this to 2004 and 2018 because college game states get foggy beyond 2000, which makes it tough to get a complete picture for QB records and games started prior to 2000. Therefore, a QB who started all four years in college and was drafted in 2003 would not provide reliable stats as I could not access the data for the 1999 season.

I then looked at how many games each QB sat on the bench during their rookie year and created graphs to depict how well each QB produced in their career versus how quickly they started games for their team.

If you would like to find a summary and scouting report on Justin Fields’ career to this point, you can find my full report here.

ANY/A+

For those unfamiliar with ANY/A+, it is basically an era-adjusted version of ANY/A. An ANY/A+ of 100 signifies that the passer was league average when compared against all passers in the years they played. Anything above 100 signifies above average, and anything below 100 signifies below average. ANY/A stands for Adjusted Net Yards per Attempt, and is calculated as follows:

(Passing Yards + Passing TDs*20 – INTs*45 – Sack Yards) / (Pass Attempts + Sacks)

EPA/Play

For those unfamiliar with EPA/Play: Expected Points Added (EPA) is a football statistic that seeks to measure the value of individual plays in terms of points. This is done by calculating the Expected Points (EP) of the down, distance, and field position situation at the start of a play and contrasting it with the situation at the end of the play. A three-yard gain on first-and-ten is pretty different than a three-yard gain on third-and-two, something not usually captured in conventional statistics. The Expected Points framework helps translate raw gains into value.

Flaws in the Methodology

  • Obviously, every QB is a different story mechanically, mentally, and athletically. Patrick Mahomes starting Week 1 could have been significantly different from him starting the 16th game of the season.
  • It is absolutely a valid belief that QBs who are ready to start Week 1 are more likely to find NFL success because they are just more pro-ready prospects and more capable players in general.
  • I have attempted to adjust for some of these flaws by looking at QB’s who are the most similar to Justin Fields in the final section.
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All First-Round QB’s from 2004-2018

Below is every QB to be drafted in the first round since 2004. The x-axis of the chart details how many games they sat on the bench prior to making their first start. The y-axis details their career EPA/Play.

Overall, there is not much difference between QB’s who started early in their rookie season versus those who started late, with a slight downward trend for those who started their first game later in their rookie seasons. However, I would like to point out a few data points and look a little bit deeper at some potential outliers.

The next section is going to look more closely at QB’s who align closer to Justin Fields in regards to collage pass attempts and college games started.

QB’s with 1,000 or Fewer Pass Attempts in College

In the below chart, we narrowed the pool of QB’s down to those who made fewer than 1,000 pass attempts in their college careers. This includes 23 QB’s who averaged 785 college pass attempts. Justin Fields threw 618 pass attempts in college, which is on par with Aaron Rodgers (665), Josh Allen (649), Carson Wentz (612), Alex Smith (587), and Mitchell Trubisky (572).

  • The group as a whole averaged ANY/A+ of 92.7 and EPA/Play of 0.029.
  • Ten of these QB’s started Week 1 of their rookie seasons. In their NFL careers, they averaged ANY/A+ of 94.4, and EPA/Play of 0.05. Therefore, the QB’s who started Week 1 fared better than the QB’s who sat for any portion of their rookie season, on average.
  • Seven of these QB’s made their first start after week one but within the first eight games of the season. In their NFL careers, they averaged ANY/A+ of 90.6, and EPA/Play of 0.026. Therefore, the QB’s made their first start between the team’s second game and eighth game fared worse than the QB’s who started Week 1, on average. It is notable here that outside of Josh Allen, who started Week 2, this group averaged EPA/Play of 0.007.
  • Four of these QB’s made their first start in their rookie seasons after the eighth game of the season. In their NFL careers, they averaged ANY/A+ of 87 and EPA/Play of -0.043. Therefore, the QB’s made their first start in their rookie season but after the eighth game have not seen good results, but are a small sample. Despite the small sample here, the results are consistent, with the QB’s being Jason Campbell, Tim Tebow, Johnny Manziel, and JaMarcus Russell.
  • Two of these QB’s did not make a single start in their rookie season. These two QB’s had very different careers. The first one was JP Losman, who sat his entire rookie season and started Week 1 of his second season. He had a career ANY/A+ of 87, and a career EPA/Play of -0.082. The other QB here is Aaron Rodgers, who sat for his first three years in the NFL. Rodgers has a career ANY/A+ of 118 and a career EPA/Play of 0.234.
  • Rodgers appears to be an outlier in this data set, as he was able to sit for three years behind Favre.
  • Among the top eight QB’s in this group by EPA/Play, only one sat on the bench beyond Week 1 — Aaron Rodgers. Josh Allen is notable here, as he started Week 2 of his rookie season.
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QB’s with 30 or Fewer Starts in College

In the below chart, we discarded the filter on pass attempts and replaced it with a filter on college games started. The below QB’s made 30 or fewer starts in the college careers. This includes 23 QB’s, who averaged 24.4 college starts. Justin Fields started 22 games in college, which is on par with Aaron Rodgers (22), Josh Allen (23), Carson Wentz (23), Joe Flacco (22), and Alex Smith (21).

  • The above group as a whole averaged ANY/A+ of 92.4 and EPA/Play of 0.025.
  • Ten of these QB’s started Week 1 of their rookie seasons. In their NFL careers, they averaged ANY/A+ of 92.7 and EPA/Play of 0.039. Therefore, the QB’s who started Week 1 fared better than the QB’s who sat for any portion of their rookie season, on average.
  • Seven of these QB’s made their first start after Week 1 but within the first eight games of the season. In their NFL careers, they averaged ANY/A+ of 87.6 and EPA/Play of -0.010. Therefore, the QB’s made their first start between the team’s second game and eighth game fared worse than the QB’s who started week one, on average. It is notable that outside of Josh Allen, who started Week 2, this group averaged EPA/Play of -0.034.
  • Three of these QB’s made their first start in their rookie seasons after the eighth game of the season. In their NFL careers, they averaged ANY/A+ of 96 and EPA/Play of 0.025. Therefore, the QB’s made their first start in their rookie season but after the eighth game have seen decent results on average, but are a small sample. The QB’s here are Patrick Mahomes, Johnny Manziel, and JaMarcus Russell. Therefore, there is a lot of variability in this group. 
  • Two of these QB’s did not make a single start in their rookie season, the same as the previous chart: JP Losman and Aaron Rodgers.
  • Among the top eight QB’s in this group by EPA/Play, the top two both sat on the bench beyond the 15th game of the season. Aaron Rodgers (three years) and Patrick Mahomes (15 games). The other QB’s in the top eight all started before their team’s second game.
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Timing of a QB’s First Start

Now, we will look at the entire pool of QB’s, sorting by when they made their first career NFL start.

  • It is interesting to see that the less experienced QB’s tend to start earlier in their careers. I suppose this could be due to the clear-cut top QB’s leaving college as high draft picks their junior year more often.
  • It appears that QB’s who made their first start in Week 1 of their rookie seasons and QB’s who made their first start in the second half of their rookie seasons have fared the best overall.
  • The difference here is marginal, which begs the question, why wait?
  • We will take a deeper look below at these groupings below.

QB’s Who Started Right Away

Below are all QB’s who started in Week 1 of their rookie season. This includes 15 QB’s who averaged 28 college starts and 897 pass attempts. Justin Fields logged 22 college starts and 618 pass attempts. I think it is fair to wonder how many games started versus seasons starting could make a difference here. Although Fields only started 22 games, he played two full seasons with his second season shortened due to COVID-19, circumstances we have never really experienced before.

  • This group averaged ANY/A+ of 96 and EPA/Play of 0.066.
  • Six of the 15 (40%) QB’s listed here had ANY/A+ of 100 or better (league average or better).
  • Six of the 15 (40%) QB’s listed here had EPA/Play of 0.10 or better.
  • Eight of the 15 (53%) QB’s listed here had EPA/Play of 0.075 or better.
  • Ten of the 15 (67%) QB’s listed here had EPA/Play of 0.050 or better. EPA/Play of 0.050 is the average for all QB’s drafted from 2004-2018.
  • QB’s in this group include Matt Ryan, Andrew Luck, Jameis Winston, Marcus Mariota, Matthew Stafford, Cam Newton, Carson Wentz, Ryan Tannehill, Joe Flacco, Robert Griffin III, Sam Bradford, Brandon Weeden, Mark Sanchez, and EJ Manuel.
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QB’s Who Debuted in First Half of Rookie Season, Not Week 1

Below are all QB’s who did not start week one, but made their first start within the first eight games of their rookie season. This includes 15 QB’s, who averaged 31 college starts and 1,016 pass attempts. Justin Fields had 22 college starts and 618 pass attempts.

  • This group averaged ANY/A+ of 91.6 and EPA/Play of 0.026. 
  • Four of the 15 (27%) QB’s listed here had ANY/A+ of 100 or better (league average or better).
  • Those same four of 15 (27%) QB’s listed here were the only QB’s to achieve EPA/Play of 0.10 or 0.075.
  • Six of the 15 (40%) QB’s listed here had EPA/Play of 0.050 or better. EPA/Play of 0.050 is the average for all QB’s drafted from 2004-2018.
  • QB’s in this group include Deshaun Watson, Ben Roethlisberger, Josh Allen, Baker Mayfield, Teddy Bridgewater, Mitchell Trubisky, Alex Smith, Vince Young, Josh Freeman, Blake Bortles, Christian Ponder, Matt Leinart, Paxton Lynch, Blaine Gabbert, and Josh Rosen.

QB’s Who Debuted in The Second Half of Their Rookie Season

Below are all QB’s who did not start Week 1, but made their first start in the final eight games of their rookie season. This DOES NOT include QB’s who did not make a single start in their rookie seasons. This includes nine QB’s, who averaged 34 college starts and 1,124 pass attempts. Justin Fields had 22 college starts and 618 pass attempts.

  • This group averaged ANY/A+ of 99.3 and EPA/Play of 0.069.
  • Four of the nine (44%) QB’s listed here had ANY/A+ of 100 or better (league average or better).
  • Three of the nine (33%) QB’s listed here had EPA/Play of 0.10 or better. 
  • Four of the nine (44%) QB’s listed here had EPA/Play of 0.075 or better. 
  • Five of the nine (56%) QB’s listed here had EPA/Play of 0.050 or better. EPA/Play of 0.050 is the average for all QB’s drafted from 2004-2018.
  • QB’s in this group include Patrick Mahomes, Lamar Jackson, Jared Goff, Eli Manning, Jay Cutler, Jason Campbell, Tim Tebow, Johnny Manziel, and JaMarcus Russell.
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QBs Who Did Not Debut Until After Their Rookie Season

Below are all QB’s who did not start a single game of their rookie season. This includes five QB’s, who averaged 37 college starts and 1,222 pass attempts. Justin Fields had 22 college starts and 618 pass attempts.

  • This group averaged ANY/A+ of 97.4 and EPA/Play of 0.043.
  • Two of the five (40%) QB’s listed here had ANY/A+ of 100 or better (league average or better).
  • Those same two of five (40%) QB’s were the only ones to achieve EPA/Play of 0.10, 0.075, or 0.050. The group’s average is 0.050.
  • Philip Rivers and Aaron Rodgers are the two QB’s who can be deemed as “successful” in this group. Both players sat multiple years behind Pro Bowl starters. Other QB’s here are Jake Locker, JP Losman, and Brady Quinn.

In Summary:

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Justin Fields Comparables:

Below are the first-round QB’s I deemed to be the most comparable to Justin Fields:

Any stat category highlighted in bright green is closely comparable to Fields’ stats and yellow is somewhat comparable to Fields’ stats, listed in order of most comparable to least comparable. I cut off the list at 30%. These comparisons take experience, production as a passer and as a runner, college success, and speed into account.

Using these comparable QBs, here is how they vary regarding how many games they sat on the bench versus how successful they were based on EPA/Play.

  • In total, there were 17 comparable QB’s. They average 24 college starts and 776 pass attempts.
  • Seven of these QB’s started week one. They averaged ANY/A+ of 96.9 and EPA/Play of 0.089.
  • Nine of these QB’s started either Week 1 or Week 2. They averaged ANY/A+ of 99 and EPA/Play of 0.106.
  • Three of these QB’s made their first start in Week 3 or 4. They averaged ANY/A+ of 93 and EPA/Play of 0.05.
  • Four of these QB’s made their first start after Week 8 but still in their rookie year. They averaged ANY/A+ of 100 and EPA/Play of 0.071. This group has a wide variance, with QB’s being Mahomes, Jackson, Manziel, and Russell. 
  • Aaron Rodgers was the only comparable QB who did not start a game in his rookie year.

Let me know your thoughts on Twitter @ButkusStats. I personally am of the belief that if Justin Fields shows the ability to handle what the Bears ask of him in training camp, he should be the Day 1 starter, and I think this data supports that opinion. But I am interested to hear what other fans’ thoughts are on this subject.


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Bryan Kolak
Bryan Kolak
1 month ago

I think you need to also look at it from the standpoint on who the competition was in college. Ohio State has a much bigger spotlight on them the a BYU or North Dakota State. He also played much better defenses. This I believe prepared him for the nfl than other QBs.

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1 month ago

[…] Not a single QB drafted by the Bears in the first round has started Week 1 of their rookie year. […]

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