The current debate about what to expect for Dak Prescott's rookie season, led me to look up how QBs who do well in their rookie years perform in year two. I started with this SI article from early last fall, which was written when it looked like both Dak Prescott and Carson Wentz would put up historic rookie seasons. Unfortunately for Carson, if you believe the narrative, his surrounding cast suddenly became unreliable after September, and consequently he couldn't keep up that historic pace for the rest of the season. The ordering of SI's list of the ten best rookie QB seasons is debatable, but there doesn't seem to me to be any notable omissions. For the purpose of this post, I did however include Marcus Mariotta, since his rookie season was pretty good, with a passer rating above 90. The table below shows stats for these players' rookie and sophomore seasons. It's a long and wide table, but you can scroll right until the end.

QB Peyton Manning Jamies Winston Andy Dalton Andrew Luck Matt Ryan Dan Marino Russell Wilson Cam Newton Robert Griffin III Ben Roethlisberger Marcus Mariotta COMPOSITE PLAYER Dak Prescott Year 1998 1999* 2015* 2016 2011* 2012 2012* 2013* 2008 2009 1983* 1984*+ 2012* 2013* 2011* 2012 2012* 2013 2004 2005 2015 2016 ROOKIE YEAR 2 CHANGE IN RAW NUMBERS 2016* 2017 Projected Age 22 23 21 22 24 25 23 24 23 24 22 23 24 25 22 23 22 23 22 23 22 23 23 24 Tm IND IND TAM TAM CIN CIN IND IND ATL ATL MIA MIA SEA SEA CAR CAR WAS WAS PIT PIT TEN TEN DAL DAL G 16 16 16 16 16 16 16 16 16 14 11 16 16 16 16 16 15 13 14 12 12 15 15 15 16 16 GS 16 16 16 16 16 16 16 16 16 14 9 16 16 16 16 16 15 13 13 12 12 15 15 15 16 16 Cmp 326 331 312 345 300 329 339 343 265 263 173 362 252 257 310 280 258 274 196 168 230 276 269 293 8.92% 311 339 Att 575 533 535 567 516 528 627 570 434 451 296 564 393 407 517 485 393 456 295 268 370 451 450 480 6.67% 459 490 Cmp% 56.7 62.1 58.3 60.8 58.1 62.3 54.1 60.2 61.1 58.3 58.4 64.2 64.1 63.1 60 57.7 65.6 60.1 66.4 62.7 62.2 61.2 59.8% 61.0% 67.8 69.2% Yds 3739 4135 4042 4090 3398 3669 4374 3822 3440 2916 2210 5084 3118 3357 4051 3869 3200 3203 2621 2385 2818 3426 3365 3632 7.93% 3667 3958 TD 26 26 22 28 20 27 23 23 16 22 20 48 26 26 21 19 20 16 17 17 19 26 21 25 19.05% 23 27 TD% 4.5 4.9 4.1 4.9 3.9 5.1 3.7 4 3.7 4.9 6.8 8.5 6.6 6.4 4.1 3.9 5.1 3.5 5.8 6.3 5.1 5.8 4.7% 5.2% 5.00% 5.6% Int 28 15 15 18 13 16 18 9 11 14 6 17 10 9 17 12 5 12 11 9 10 9 13 13 0% 4 4 Int% 4.9 2.8 2.8 3.2 2.5 3 2.9 1.6 2.5 3.1 2 3 2.5 2.2 3.3 2.5 1.3 2.6 3.7 3.4 2.7 2 2.9% 2.7% 0.90% 0.84% Y/A 6.5 7.8 7.6 7.2 6.6 6.9 7 6.7 7.9 6.5 7.5 9 7.9 8.2 7.8 8 8.1 7 8.9 8.9 7.6 7.6 7.5 7.6 7.99 8.08 Y/G 233.7 258.4 252.6 255.6 212.4 229.3 273.4 238.9 215 208.3 200.9 317.8 194.9 209.8 253.2 241.8 213.3 246.4 187.2 198.8 234.8 228.4 224.3 242.1 229.2 247 Rate 71.2 90.7 84.2 86.1 80.4 87.4 76.5 87 87.7 80.9 96 108.9 100 101.2 84.5 86.2 102.4 82.2 98.1 98.6 91.5 95.6 86.6 90.6 104.9 108.4

Of the 11 QBs listed here, only two had worse statistical seasons in year 2 - one marginally, in Matt Ryan and one by a significant margin, in Robert Griffin III. However, far more of these QBs improved in year 2. All of the remaining 9 QBs actually improved their passer rating in year 2, some marginally (essentially a similar performance to their rookie years) while others, such as Dan Marino and Peyton Manning, made dramatic improvements in year 2. The areas that show the most differences in performance from years 1 to 2 are passing yards and touchdowns, perhaps because as these QBs moved to their second year, the playbook was opened up for them. Interestingly, six of these 11 QBs actually reduced their interceptions, and those who did not, had an increase in touchdowns, with the notable exception, again, of RG3. So we have 9 QBs either repeating or building on their good rookie years, with 2 regressing. This contradicts the conventional wisdom that rookie QBs who do well should be expected to take a step back. Prescott had arguably the best rookie season of all of these QBs, but should he be penalized in expectations simply because he did so well as a rookie? I would argue no, especially since the QB with the previous best rookie season, according to SI, Ben Roethlisberger, built on his impressive rookie season and took his team to the Super Bowl in his second year.



What can we expect from Dak in year 2 based on these 11 QBs?

To get a sense of what kind of season Dak would have in year 2 if his year 2 season was a reflection of the "average" of these 11 players, I created a "composite QB", whose raw numbers (completions, attempts, yards, TDs, INTs) were an average of the numbers of the 11 QBs for their rookie and sophomore seasons. I then used the percentage change in these raw numbers from the composite QB's rookie season to his sophomore season, to project the raw numbers Dak could have in 2017, shown below. These projected raw numbers were used to calculate his projected efficiency stats, such as passer rating.

Tm G GS Cmp Att Cmp% Yds TD TD% Int Int% Y/A Y/G Rate DAL 16 16 339 490 69.2% 3958 27 5.6% 4 0.84% 8.1 247 108.4

Is is reasonably to expect that Dak's second season will show the same improvement as these QBs made, on average? Perhaps not, but it sure seems a lot more reasonable than suggesting Dak's sophomore season will be like Griffin's, when RG3 is a clear outlier among his peers. Nobody suggests that Dak's second season will show the kind of dramatic improvements that Dan Marino's (also an outlier among these QBs) did. Why then are people quick to hang their hats on Dak's second season turning out like RG3's?

Another interesting group of QBs to compare Dak with is shown in the graphic below from ESPN:

Dak had the second highest passer rating over a QB's first 16 games (which also includes non-rookie performances). Every QB (besides Dak) in the top 5 in this stat took their teams to the Super Bowl in year 2. Of course, this is a very small sample size and doesn't mean the Cowboys are necessarily headed to the Super Bowl this year. But it does indicate to me, in addition to the performances of the 11 QBs above, that the logical expectation for Dak's sophomore season should be at the very least, a similar performance to his rookie year. The dataset of QBs show have started their careers as well as Dak has, does not support the conclusion that his performance in 2017 is likely be worse than his rookie year.