In my previous post, I mentioned that one of my biggest concerns about the roster is that staging of the “rebuild” might be disjointed. In other words, the Eagles have a lot of good players, but I’m worried there aren’t enough of them that will be in peak form (or close to it) at the same time, lowering the potential ceiling of the group.
While I still have a lot of work to do to explore this issue, it seemed natural to begin with a look at Jason Peters. He is one of the best players on the team (arguably THE best), a potential future HOFer, and a keystone of Chip’s dominant running attack. He’s also going to be 33 years old this year. How much longer can he be expected to play at a high level?
There are a few ways to dig into this, but I began with the simplest. I used Pro-Football-Reference.com’s Approximate Value measure as a proxy for impact/skill. I searched for all OTs, post-merger, who registered a combined Approximate Value of at least 20 in their age 31-32 seasons. Basically, I was looking to get a sample of Tackles who played as well as Peters has this late in his career. There were 15 such players. I then looked at how those players progressed. The results, unfortunately, were not encouraging. I rebased the annual AV of each player to their age 32 season value. I then took an average of those to get an aggregate aging curve.
Below is a chart illustrating the analysis. The blue line illustrates the performance progression. The red bars show how many players remained in the analysis each year. Studies like this are highly sensitive to survivorship bias, so I wanted to make it very clear how few of these players remained in the league as they got older. In general, this effect serves to OVER-estimate the contributions of players as they age (unless you make adjustments for it, which I have not done here).
Jason Peters is entering his Age 33 season. The 15 tackles I looked at, on average, recorded an Approximate Value in that season of just 73% of their age 32 season. Also note that by age 36, just 4 of the 15 players were still playing, and beyond that, only Lomas Brown continued.
This is obviously a very rough analysis. OL contributions are very difficult to quantify and Approximate Value isn’t a perfect statistic. Also note that Jason Peters’ AV last season was 12. Just 60% of that would still result in an AV of 7.2. By comparison, Lane Johnson’s average AV over the past two years is 7. The takeaway is that even if Jason Peters follows the above progression exactly, he can still be a decent contributor for another year or two. Expecting much beyond that, however, seems irrational.
Now let’s take a less systematic look at things. I also searched the PFR database for all post-merger OTs that recorded an AV of at least 7 in the seasons corresponding to the following ages, which are shown with the number of players meeting that threshold:
34 yrs – 36 players
35 yrs – 23 players
36 yrs – 6 players
37 yrs – 4 players
38 yrs – 3 players
As you can see, it’s extremely rare for OTs to have a great season beyond the age of 33, and it almost never occurs after age 35. The conclusion is that we shouldn’t expect Peters to play at a high level for more than another 1-2 yrs, and if he plays longer than that, it might be due as much to a failure of finding a decent replacement as to his ability.
A few other notes (all post-1970):
– Willie Roaf recorded an Av of 17 when he was 34 yrs old.
– Just 4 tackles made the All-Pro 1st team after age 33: Walter Jones (33), Mike Kenn (35), Willie Roaf (34), and Gary Zimmerman (35). Each of them was also drafted in the 1st round (not saying that means anything, just thought it was interesting).
– 25 OTs made the pro bowl after turning 33 (includes multiple appearances by the same player).
– OTs older than 35 have started at least 12 games 49 times (36 different players).
Your work’s so damn good. And your sabbatical’s increased the “savor” value of your posts.
Completely on board with your take-away in the prior post that lost of fanatics may be disappointed by Bradford.
As you suggested (or it seemed, at least), even assuming a below-average supporting cast, Bradford’s career numbers are not particularly good.
You’ve got a hell of a ffertile mind.
QUESTION: what’s your agenda after LS/MBA?
Thanks for the kind words. I’m hoping to take a closer look at Bradford soon, and still want to take the aging curves further. As for after school, no defined plan yet.
So I think the obvious nextt auestion is: how can the miracle of sports science! Change the odds? I can’t imagine more than a year or so because the cliff looks so precipitous at that age. But it’s interesting uncharted waters. I’m also wondering when all the older lineman you looked at played. I get its post 1970, but then current sports science and incentives to keep playing may make a difference also. Again, it’s tough to imagine really good line play deep,into the 30s, but if we’re talking championship,windows, a year extra could be a big deal.
Re career: interesting that you haven’t fallen for the big firm route with your background. You should probably just monetize your blog. Bound to make bank that way.
This is really great stuff. I love how clever and thorough Eagles commentary has become the last few years. My concern is that you might just be picking up reversion to the mean here. If you pick tackles that score > 20 on AV, regardless of age, and then look at how they perform in the next few years, you might expect that they will decline as a group. Run the data for the tackles with AVs > 20 a year earlier, two years earlier, three years earlier, etc. Do you still see decline? (I wouldn’t be surprised if you did.)
It is also worth mentioning that 73% of Jason Peters may still be a Pro Bowl tackle. The dude is a beast!
So I guess this blog is dead then, huh? RIP Eagles Rewind. You were fun while you lasted.
Not dead. Just sporadic for the time being.