The Mahomes Experiment: Do NFL Quarterbacks Benefit from Sitting their Rookie Seasons

Last year, Chiefs general manager John Dorsey intentionally sat first round rookie quarterback Patrick Mahomes so that the young star could learn under veteran QB Alex Smith, a move that was questioned at the time. Now, as Mahomes is having a breakout year and has the Super Bowl in his sights, Dorsey is being praised for his patience and foresight.

After transitioning to GM of the Cleveland Browns in the offseason, Dorsey attempted to use the same formula, announcing that number one overall pick Baker Mayfield would sit out his rookie season to learn under Tyrod Taylor. However, that plan came crashing to a halt when Taylor suffered a concussion late in the first half of the Browns’ week 3 matchup against the Jets, and Baker Mayfield was forced to enter his first NFL game down 14-3 at the half.

Baker

Incredibly, Mayfield mounted a comeback to defeat the Jets, and was able to secure the Browns’ starter position for the remainder of the 2018 season. In this situation, many critics argued that Mayfield was NFL-ready from day 1. “He doesn’t need the Mahomes treatment!” they cried. And the evidence is pointing in their favor—Mayfield has been impressive this year.

These two recent cases have called into question Dorsey’s (and others’) philosophy that sitting a rookie QB for a year makes them more “NFL-ready”. Does a quarterback truly perform better in his first year starting if he sits out his rookie season, or does it not make a difference?

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I want to examine this question through a historical lens, comparing past quarterbacks who were thrown straight into the fire and started their rookie season to quarterbacks who did not become a starter until their second season (who I will call “sophomore starters”). I am also only examining the quarterbacks’ statistics during their first year as a starter. Basically, we’re just testing whether “NFL-readiness” is increased by “the Mahomes treatment”.

            Of course, there are some shortcomings to this approach. Some quarterbacks are simply better, and will be stars in the NFL regardless of their role during their rookie seasons. I don’t think anyone can argue that Payton Manning should have sat his fiery 1998 rookie season—Manning was top 5 in touchdowns and passing yards as a rookie. To account for differences in talent, I separated 1st round quarterbacks from non-1st round quarterbacks and examined the groups separately. I also used a large sample size, looking at quarterbacks drafted from 1988 to 2016 in an effort to soften the impact of breakouts like Manning or duds like Jimmy Clausen, who was eternally banished to NFL backup status after a dismal rookie season with the Panthers in 2010.

JClausen

I picked four statistics to judge a quarterback’s entire first year performance: Completion %, Touchdown %, Passer Rating, and Adjusted Net Yards per Attempt. These statistics certainly do not capture a quarterback’s entire season’s performance, but they do a good job summarizing it. Completion % indicates a quarterback’s accuracy, TD % illustrates a quarterback’s ability to actually score, and passer rating acts as an overall analyzer of performance. Finally, adjusted net yards per attempt, or ANY/A, shows a quarterback’s deep ball ability with an emphasis on touchdowns and a penalty for interceptions. For example, here is prolific passer Carson Wentz’s rookie year performance in those categories:

CWentz

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When I looked at the performance of all of the first-round quarterbacks since 1988, I split them into two groups to compare: rookie starter and sophomore starters, and then compare the average rookie starter stats to the overall first round stats and see if there is a significant difference (and do the same for the sophomore starters). Through my findings, Byron Leftwich embodies the average 1st round rookie starter; he is right around the average for this group in all four stats. As for 1st round sophomore starters, JaMarcus Russell is our middle-man. As you can see below, the two quarterbacks put up shockingly similar statistics in their first seasons as starters (and just for fun, I will include Ben Roethlisberger’s monster 2004 rookie season).

BLeftwich

JRussell

BRoethlisberger

These two similar examples confirm the findings of my statistical analysis—there is no significant evidence that sophomore starters perform differently than rookie starters among first rounders! The slight variations in the averages that you see below are not considered “statistically significant,” which is nerd talk for ‘not big enough to be conclusive.’

Screen Shot 2018-12-12 at 3.00.28 PM

The average later rounders are shown below; Derek Carr and Tyler Thigpen characterize their respective groups very well.

DCarr

TThigpen

Again though, my statistical analysis finds no significant difference between the rookie starters and the sophomore starters—the averages for both groups practically mirror the averages for all later round quarterbacks.

Screen Shot 2018-12-12 at 3.00.36 PM

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I’m certainly not saying that every rookie quarterback should start, or that John Dorsey is an idiot (quite the contrary, I actually love what Dorsey has done for the Browns). Maybe Patrick Mahomes really did play better because of his time as a backup, and that could be true for other quarterbacks as well. However, historically, there is no conclusive evidence that quarterbacks who have a season to sit and learn perform better in their first season as a starter. With an exciting group of college quarterbacks including Dwayne Haskins and Tua Tagovailoa entering the draft in the next few years, it will be interesting to see whether GM’s continue to deploy the ‘Mahomes treatment’—who knows, maybe we will see the next Ben Roethlisberger light it up in their rookie season!

Sources

Stats:

http://www.drafthistory.com/index.php/positions/qb

https://www.pro-football-reference.com/years/

https://www.si.com/nfl/photo/2016/10/11/best-rookie-quarterback-seasons-nfl-history#1

https://www.sportingcharts.com/dictionary/nfl/adjusted-net-yards-per-pass-attempt.aspx

Photos:

https://deadspin.com/yep-patrick-mahomes-is-still-ridiculous-1829257500

https://www.crimsonandcreammachine.com/2018/9/21/17886428/oklahoma-sooners-football-baker-mayfield-cleveland-browns-shirt-cleveland-special-rally-possum

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