When is your really great old quarterback too damn old?

"Old" can be a moving target in football, but it’s one we still generally have pinned down. Running backs are considered old at the age of 30, which is why, if they’ve been handling a steady workload throughout their career (hi there, Chris Johnson), we begin to talk about decay at the depressingly early age of 28. 

Wide receivers last a little longer, but as we’ve seen with the likes of Randy Moss and Chad Ochocinco/Johnson in recent years, their abilities decline steeply at around age 35.

Then there are the quarterbacks, those weird, timeless beings. The most talented among them can stay effective well into their late 30′s. If there’s an average offensive line in front of him, a good quarterback won't get laid out too often and add a few years, too. But arm strength still fades, as does the mobility or foot speed required to avoid a rush. 

So, every year, the few teams riding a true generational talent at QB wrestle with a key question as the draft nears, and selecting an heir to the throne with a high pick is an attractive option:

When is your really great old quarterback too damn old?

Here's the awful truth: three of the best quarterbacks in this era — Peyton Manning, Tom Brady, and Drew Brees — will all be at least 35 years old before the start of next season.

At 38, Manning is too far removed from his best days, a fact both his birth certificate and body confirm. His arm strength is wobbly at best, and although he can still make the odd deep throw when needed, the success of the Denver Broncos offense this past season was rooted in a system structured around high percentage quick throws. Receivers were put in space to gain yards after the catch, and often Manning would get them that open green through audibles with his pre-snap eye. His mind at least is still sharp as ever.

Manning is the elder statesman of the quarterback union, with emphasis on the elder; he's had four neck surgeries, the season he missed not too long ago, and he has a yearly check-up to determine his football fate.

So why don't we paint the aging Tom Brady with the same brush? Maybe it’s his bro-ing out with Snoop Dogg, his shameless water slide glee or his boyish looks. But Brady is old, he’s just not playing old yet, and the distinction there is both important and confusing for the draft heir discussion.

Just after training camp starts Brady will officially be in his 37th year. He’s far closer to Manning’s age than anyone should be comfortable with, a reality Brady would very much like to avoid. He's been asked about his impending fate every August, and last summer Brady let out a resounding “meh“, saying that, barring a catastrophe, he might play to 40 and beyond.

There’s the problem for Bill Belichick et al, though it’s the very best kind of problem. In 2011 Ryan Mallett was drafted at a reasonably high investment (a third-round pick), and this fall he’ll enter the final season of his rookie contract. Mallett almost certainly doesn’t want to waste the prime of his career as Brady’s backup, and he’ll be lured elsewhere by both a starting opportunity and the sweet cash which comes with it.

When that inevitably happens, Brady will have no promising backup waiting to take his place, and in his 38th year he’ll still be signed through the 2017 season. Given Brady’s age and Mallett’s expiring contract, the Patriots have a few things to look at on May 8th to 10th: is a quarterback we like available to us? Can he wait and learn for a few years? Is his name A.J. McCarron, or further down Aaron Murray?

Or maybe the Patriots make a risky late-first round pick on a quarterback if the right arm is waiting (David Carr?), though I’m not sure they has reached the point Green Bay was years ago when improvements elsewhere on the field were sacrificed to carry an expensive backup.

The Broncos have seen plenty of Brock Osweiler at this point in practice and during the preseason, and reports last summer indicated he was much improved. But a year from now he’ll be entering the final year of his rookie contract, putting a deadline on a decision regarding his future. If they’re not confident that he’ll provide post-Manning stability, drafting another quarterback early-ish now buys both more time, and another lottery ticket.

In New Orleans the tussle with this delicate question is just a little further off with Brees 35 years old, but a decision there is coming too. Though Manning’s wonky neck is the most troubling, all three of our aging heroes have suffered major injuries at one point in their careers.

All three also occupy spaces in the top 10 career passing yards list. But with the exception of the stubborn and superhuman Favre who played until the age of 41 (and Vinny Testaverde defying all time laws and lasting to 44 somehow), their neighbors on that list all have something in comon: Dan Marino, John Elway, Fran Tarkenton, Joe Montana, and Phil Simms retired at 38. Of the top 20, seven made it past that age-38 cutoff (counting Warren Moon who didn’t start his NFL career until he was 28).

So there’s some hope and time yet. Just not much.