For the most part, age is rarely discussed when talking about college quarterbacks. Outside of the Brandon Weedens and Chris Weinkes of the world, you generally don’t hear much from the draft community about the age of a prospect. But we do know that age matters, and that all other things being equal, being younger is better (or a sign that the player has a higher ceiling).

In this year’s draft, Tyler Bray is the neophyte, as he’ll be 21 years and 8 months old at the start of the season. He’s just weeks older than Matt Stafford and Josh Freeman were this time four years ago. It also means he’s 10 months younger than Geno Smith, the second youngest of the top prospects. On the other hand, Tyler Wilson will be 24 when the season starters, Landry Jones just turned 24, and Jordan “did you know Aaron is my brother” Rodgers will be 25 on August 30th. Do NFL teams generally ignore age — i.e., fail to measure younger quarterbacks against a lower bar? Or perhaps do they overemphasize age, thinking a young player has such high upside and can be taught anything that they ignore red flags? That’s what this post seeks to answer.

From 1970 to 2008, 587 quarterbacks were selected in the annual NFL draft. Unfortunately, I don’t have data on the age of the 195 players who never made it on to an NFL field. ^[1]The highest drafted quarterback never to appear in a game since 1970 was Arkansas State’s Gene Bradley, who was selected with the 37th pick by the Bills in 1980. However, I do have the dates of birth for the remaining 392 quarterbacks, which let’s us investigate how NFL teams value age.

First, we need to grade how well the quarterbacks performed. I decided to evaluate players through their first five seasons only, as I think that’s what teams consider when they select a player in the draft. I used a modified version of the formula from my Greatest Quarterback of All-Time Series: for each quarterback, I calculated his Adjusted Net Yards per Attempt average and the league ANY/A for each of his first five seasons. I then gave each passer credit for his ANY/A over replacement level — defined as 75% of league average — and multiplied that differential by his number of pass attempts (including sacks) to create a “value over replacement” statistic.

That’s a fancy way of saying I figured out which quarterback provided the most passing value over replacement in his first five years. Note that I did not include rushing in an attempt to keep it relatively simple. The results aren’t very surprising: Dan Marino has a huge lead on everyone else, with Peyton Manning and Matt Ryan at #2 and #3. Next, I converted the draft values from my Draft Value Chart into expected “adjusted net yardage over replacement” figures for these quarterbacks. After doing that, we can compare how much value above or below expectation each quarterback provided. Here are the results: the final column shows the player’s age on September 1st of the year he was drafted.

Next, I plotted each quarterback on a graph, with age on the X-axis and the Differential column (value over replacement over expectation) on the Y-axis. Note that Dan Marino’s data point is off the chart, but he was included in the underlying file.

It’s pretty easy to see that there’s no relationship between age and draft selection. If teams undervalued age, then more of the dots would be up and to the left; if teams overvalued age, then there would be a disproportionate number of dots down and to the right. I’ve included a best-fit trendline in a thick black line, and as you can see, it essentially rides along the expectation line, confirming that NFL teams have not been under- or over-valuing age.

This doesn’t mean that age is irrelevant, but rather that NFL teams are properly balancing age with every other variable. If you believe the draft is an efficient market, this would reinforce that belief. Players like Michael Vick, Alex Smith, and Drew Bledsoe were first overall picks in part because of their age. So if Tyler Bray gets drafted earlier than you might expect, that’s a sign that an NFL team considers his track record in connection with his youth. On the other hand, if he falls in the draft, it’s unlikely that it’s because NFL teams ignore his age: it just means that his youth can’t compensate for his other issues. Mock drafters and draftniks may undervalue age (at least, in my opinion) but it doesn’t appear that NFL teams are guilty of the same mistake.