Valuing a Backup Quarterback: Should the Bengals Trade AJ McCarron?

Backup quarterbacks are a hot commodity around this time of year, but their play might not be worth the intrigue.

For some, the backup quarterback position is the best in football -- you make a significant amount of money to be on an NFL team, stand on the sidelines and see limited playing time. 

For others, the backup quarterback is their favorite player on the roster -- a beacon of hope when the starter fails to reach expectations. 

For some general managers, backup quarterbacks are some of the most sought after trade commodities -- a potential waiting to be tapped and unleashed.

The time between free agency and the draft is peak backup quarterback season. We’ve already seen Kansas City backup Chase Daniel sign for three years and $21 million to be the backup to Sam Bradford (and maybe eventually the starter). There’s even been trade rumors over the past few weeks for players such as Cincinnati’s A.J. McCarron and Tampa Bay’s Mike Glennon. There might even be some interest for Zach Mettenberger in Tennessee. 

Not only is there interest from the outside, teams with these backup quarterbacks tend to hold on tight and treat these players like a vintage baseball card collection encased in plastic and put in a safe tucked away in a closest.

And it's really kind of odd.

Because backup quarterbacks aren’t always what they’re hoped to be. And that showed in 2015.

Backing It Up

We’ll take a look at these quarterbacks by examining how they performed by our Net Expected Points (NEP) metric. NEP, for the uninitiated, measures the value of each play on the field based on how an average team would be expected to score in each scenario using historical data. 

The following table is a list of 10 quarterbacks who dropped back at least 100 times for the same team after not beginning the season as the starting signal-caller. Quarterbacks who threw passes for more than one team such as Brandon Weeden and Ryan Mallett were not included to keep play within one team.

Team QB Dropbacks Pass NEP Rank (of 46) Pass NEP/DB Rank (of 46)
CIN A.J. McCarron 131 18.41 30 0.14 12
RAM Case Keenum 129 12.58 32 0.10 21
DAL Kellen Moore 109 9.83 34 0.09 22
DEN Brock Osweiler 298 22.83 28 0.08 26
CLE Johnny Manziel 243 -4.35 35 -0.02 35
SF Blaine Gabbert 307 -9.15 40 -0.03 38
PHI Mark Sanchez 100 -5.17 37 -0.05 41
DAL Matt Cassel 218 -31.24 44 -0.14 42
TEN Zach Mettenberger 179 -43.14 45 -0.24 45
CLE Austin Davis 105 -27.19 43 -0.26 46

What we can see from this table is most backup quarterbacks who are forced into playing time are quite bad. But the numbers in this table does reflect kindly on the play of McCarron during his limited time as the starter in Cincinnati. Among the 46 quarterbacks who dropped back at least 100 times last season, McCarron’s 0.14 Passing NEP per drop back ranked 12th, between Eli Manning and Ryan Fitzpatrick. Only three other backups posted positive Passing NEP per drop back (the average last season was 0.11, for reference), so it might not be crazy to see why the Bengals would like to hang on to a capable player behind Andy Dalton

On the other hand, McCarron seems like the exact type of player quarterback needy teams would overpay for in a trade, which could provide Cincinnati with some surplus value in draft picks if they did choose to explore the trade market.

Cincinnati wouldn’t need to look much further than Brock Osweiler, who had the fourth highest Passing NEP per drop back among these quarterbacks. Able to hit free agency, Osweiler received four years and $72 million to leave Denver and start for the Houston Texans. Osweiler more than doubled McCarron’s drop backs on the season, but McCarron doubled the efficiency on the field. Teams often draft backups like this in an attempt to develop these players into a future starter. Many successes turn out like Osweiler, where that development turns into a starting spot with another team. That’s a risk the Bengals are taking with McCarron, though there are still two years of team control on McCarron’s rookie contract.

Split the Difference

Not all opportunities are created equally, though. Some of these players get thrown into horrible situations, while others get a little more talent around them. While we can see how these backups played compared to each other, what might be a little more useful is to compare how these backups played against the starter in a similar situation.

The table below looks at both how the backup played last year -- as well as how the starter played -- and then the difference in efficiency:

Team QB Pass NEP/DB Starter Pass NEP/DB Difference
RAM Case Keenum 0.10 Foles -0.17 0.27
DAL Kellen Moore 0.09 Romo -0.04 0.13
DEN Brock Osweiler 0.08 Manning -0.02 0.10
SF Blaine Gabbert -0.03 Kaepernick -0.04 0.01
DAL Matt Cassel -0.14 Romo -0.04 -0.11
CLE Johnny Manziel -0.02 McCown 0.10 -0.12
PHI Mark Sanchez -0.05 Bradford 0.08 -0.13
CIN A.J. McCarron 0.14 Dalton 0.35 -0.21
CLE Austin Davis -0.26 McCown 0.10 -0.24
TEN Zach Mettenberger -0.24 Mariota 0.07 -0.31

Only four backups last year outperformed the starter by Passing NEP per drop back. What’s slightly interesting is two of those four -- possibly three pending trade negotiations for Colin Kaepernick in San Francisco -- are in line to be starting quarterbacks for the 2016 season. 

We already discussed Osweiler cashing in with the Texans, but Keenum is able to take advantage of the poor play of Foles to -- at least at the end of March -- be considered the Rams starter for the upcoming season. Keenum might not be the long-term answer in Los Angeles, but there's some type of logic behind the Rams’ insistence on making him the starter. 

This comparison against the starter’s production also puts a little damper on the McCarron hype train. Andy Dalton has long been a slightly above average quarterback -- at best -- during his career, but surrounded by the talent of the 2015 Bengals, Dalton was the most efficient quarterback in the league by Passing NEP per drop back. Only two players played at a bigger drop-off than the starter than McCarron, though -- Mettenberger from Mariota in Tennessee and Austin Davis during his short stint of playing time in Cleveland.

The question then gets raised whether McCarron legitimately played well last year, or if he was aided by one of the best offensive supporting casts in the league. The production of Dalton and the drop-off to McCarron would hint towards the latter. It’s a common line to be figured out for these teams -- the value of backup now and in the future against that of any draft pick compensation that may be acquired in a trade. 

It cost the Bengals a fifth-round pick in 2014 to select and develop McCarron, and they’re likely to come out ahead in value should they listen to some of the offers rumored to be coming in from these quarterback needy teams.