History lesson: Trading for a franchise QB is a huge gamble

There is very little argument the most valuable commodity in the National Football League is a franchise quarterback, and there is absolutely no argument they are few and far between.

By my count there have been just 13 over the past 20 seasons, 14 if you include Tony Romo, who I suppose is on the cusp of joining this group:

Tom Brady, Peyton Manning, Brett Favre, Drew Brees, Aaron Rodgers, Kurt Warner, Ben Roethlisberger, Russell Wilson, Eli Manning, Patrick Mahomes, Philip Rivers, Donovan McNabb and Andrew Luck.

Ten of them have rings, and the fact that Rivers, McNabb, Luck and Romo don't is probably more about the teams they played with than their own performances.

Twenty-one teams haven't had a franchise quarterback in the last 20 years and only the Packers and Colts have had more than one.

Finding a franchise QB is not the only way to win a Super Bowl; check out the ring fingers on Nick Foles, Joe Flacco, Brad Johnson, Trent Dilfer, Mark Rypien, Jeff Hostetler, Doug Williams and Jim McMahon.

But it is probably the best way, as only Foles, Flacco, Johnson and Dilfer are guys who weren't franchise QBs to win a Super Bowl in the last 20 seasons.

So how much is one of these rare gems worth?

According to Les Snead, Sean McVay and the Los Angeles Rams, it is as much as five first-round draft choices, two seconds and three thirds - what they essentially just paid for Matthew Stafford, who is not yet a franchise QB but is also on the cusp. The Rams clearly believe he will arrive now that he is in Tinseltown.

For those of you that had forgotten the Rams traded up from 15th in the first round to first in 2016 to select Goff by sending two ones, two twos and two threes to the Tennessee Titans, who had used the No. 2 overall pick the year before to draft Marcus Mariota.

Now the Rams have added two more first-round picks and a three to all of that to acquire Stafford. Can he possibly be worth it?

History tells us there's not a chance, and here's where this gets very interesting.

The franchise guys on my list arrived with the team that drafted or signed him, with the exception of Favre and Brees.

Favre cost the Packers one first-round pick and had thrown just four NFL passes when they dealt for him, and Brees was signed by the Saints as a free agent, coming off shoulder surgery after a pedestrian start to his career in San Diego.

Only the Mannings and Luck were No. 1 picks and McNabb (2), Rivers (4) and Mahomes (10) were the only other Top 10 picks.

Roethlisberger was the 11th pick in the first round, Rodgers went 24th, Brees and Favre were second-round picks, Wilson a third rounder, Brady famously went at 199 in the sixth round, and Warner and Romo were undrafted rookie free agents.

Acquiring one of these guys is much more about luck than talent, skill or strategy.

Eighty-six percent of them over the past two decades have been acquired through the draft or as undrafted rookie free agents.

And perhaps most importantly, no team in the modern era of the NFL has traded for an already accomplished NFL QB and had him become a franchise quarterback, and of those eight pedestrian signal callers with rings, none were acquired via trade.

So, if you're thinking about trading for one of those hot veteran QBs now dominating NFL trade buzz ... buyer beware.

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