The legal tampering window, in which teams can openly negotiate with free agents from other teams, is almost upon us.  When the window opens, quarterback needy teams will be scrambling to make their pitch to the crown jewel of this year’s free agent class, Drew Brees Jimmy Garoppolo Kirk Cousins.

Even though he’s widely regarded as the top available free agent in this class, Kirk Cousins has been the subject of very polarizing debate.  On one side, you have people pointing to Cousins’ productivity since becoming the full-time starter in Washington.

To sum up, Kirk Cousins key numbers (since he became full-time starter in 2015):

Games: 48 (T-1st)
Completion %: 67.02 (3rd)
Yards: 13,176 (4th)
TD passes: 81 (8th)
Rushing TD: 13 (3rd)
QB Rating: 97.5 (6th)

Is that worth top QB money to you? If not, guess idk what is.

— Sayre Bedinger (@SayreBedinger) February 13, 2018

On the other side, you have people pointing out that volume stats alone may not be the best evaluative tool for judging the quality of a quarterback.

https://twitter.com/spokenflow22/status/971882766496223233

Before everyone retreats to their corner of the “Is Kirk Cousins Elite?” debate, please know this post is not about him.  If you’d like to read in depth breakdowns on Mr. Cousins, please check out Matthew Coller‘s work for ESPN 1500 or Nick Olson‘s work at Vikings Territory.

What is a Franchise QB?

Is Kirk Cousins a franchise QB?

— Jordan Reid (@JReidNFL) February 27, 2018

If you take a moment to review the replies to J.R.’s tweet, it becomes quickly apparent that the term “franchise QB” is one whose meaning can change dramatically from person to person.  Because everyone has their own subjective definition, we spend the majority of our time talking past one another.

File photo by Matthew Healey/UPI

In my opinion, a franchise quarterback is one who consistently elevates his supporting cast (vs being propped up by them).

My methodology for defining the relationship between a quarterback’s performance and his supporting cast to test my definition of a franchise QB is as follows:

1. Pulled game by game PFF grades for 2016 and 2017
2. Determined the correlation for the grade of each position on offense to that of the quarterback
3. Weighted the grade for each offensive player by his snap share and positional value relative to QB performance
4. Aggregated the data for all teams and ran a linear regression between QB performance and supporting cast (Excel actually did all this)
5. Created an expected QB performance “model” based on the strength of team supporting cast (h/t Eric Eager)

I know I know I know… you didn’t click on a football article to learn about math.  If you’re still with me, this what I found:

1. The relationship between supporting cast and QB performance is (obviously) very strong.
2. Quarterbacks who can consistently outperform their supporting cast are very rare.
3. Over the past 2 seasons, only Russell Wilson has been able to consistently overcome a below average supporting cast to post above average performance.
4. Tom Brady and Drew Brees have had strong supporting casts and still outperform expectation by a wide margin.
5. Pat Shurmur and Kevin Stefanski coached Sam Bradford and Case Keenum to the 3rd and 9th best seasons over expectation in 2016 and 2017 respectively.

While the term franchise quarterback is thrown around a lot, my findings show that there are only three QB who’ve been able to outperform their supporting casts over the past two seasons: Russell Wilson, Tom Brady, and Drew Brees (though Andrew Luck and Aaron Rodgers would likely be in the conversation if healthy).  Matt Ryan and Philip Rivers are a in a tier slightly below Elite.

With free agency about to open and elite QBs who can outperform their surroundings being such a rarity, is it time for NFL teams to adopt a new strategy when it comes to paying the non-elite options?

Thanks for reading.

Feel free to hit me up @brownjayson on Twitter with any questions, comments, or concerns.

Data dump:

2016-2017 QB Performance Over Expectation Rankings

2017 season

2016 season