Is the NFL ageist against running backs?

My gut instinct tells me that NFL running backs are some of the most poorly treated athletes in the world of sport. The rules against hurting running backs are significantly less strict than those for wide receivers or quarterbacks which leads to a significantly larger amount of career ending injuries. Teams know the fragility of running backs and are less inclined to offer them guaranteed money on their contract (money which will be given even in the case that a player cannot keep playing due to an injury) which significantly lowers the career earnings of an unlucky running back. Further to that, coaches treat running backs as expendable due to the simplicity of their task and will often drop an injured one for a healthier model, which due to the pyramid scheme nature of the NFL there will always be.  Given enough data and enough time I would like to prove all of the above is true.

However for this post, I want to show that a running back’s age affects their ability to play in the league. Not only that as a running back gets older they are less likely to get a job, but simply being on the wrong side of 30 will dramatically reduce their chance of having a job.

What I have: A database of all players currently active in the league, and a historic database of all drafted players.

What I’m going to do with it: See that running backs over 30 are disproportionately cut from NFL rosters compared to other skill positions.

 

darren-sproles-nfl-philadelphia-eagles-indianapolis-colts-850x560


 

Many people believe that a good running back can’t be taught, that it is simply a matter of innate ability. In Paul Zimmerman’s ‘The New Thinking Man’s Guide to Pro Football’ he talks to Red Grange, the Chicago Bears’ running back in the 1930’s.

Ask Red Grange to detail the moves he made on that 60 yard touchdown against Michigan and he’ll look at you blankly.

“I was never taught to do what I did, and I know I couldn’t teach anyone else how to run,” says the great halfback. “I don’t really know what I did, and I’d have a hard time telling you what I did on any individual run, even if it’s one of the runs that everyone always talks about.

“I read about my change of pace, and it was news to me that I ran at different speeds. I know I used to have a crossover step, and I had an instinctive feeling about where the tacklers were. I read that I had peripheral vision. I didn’t even know what that meant. I had to look it up”

The running back is, in some senses, the most straightforward position in the NFL. The job is to take the ball when given it and run towards the opponents endzone. Running backs will sometimes run directly into the line at full speed through 300 pound linemen, with several linebackers running directly at them. Then in other cases the running back will do an outside run, or get through the line, only to be speared by a safety or cornerback coming at full speed to crush them.

So in some senses, the running back is the most straightforward position in the NFL. But in a lot more senses, it is a terrifying, unenviable and dangerous job. The simplicity leads to there being a long list of running backs edging for their shot in the NFL. The danger leads to an even longer list of people whose professional careers were cut short – or for college players never started – due to an irreversible injury sustained on the field.


 

I want to prove that running backs are treated as disposable more often than other skill positions. A skill position is any position which does not have much interaction with the line of scrimmage. In this article, we are using three different skill positions:

  • Wide Receiver: The wide receiver is the quarterback’s main target in the passing game. So the bulk of their work is to get open and catch balls.
  • Defensive Back: A defensive back can be either a cornerback or a safety. A cornerback will be in charge of covering a wide receiver on passing plays to try and stop the pass or tackle the receiver and the safety will generally stay further back just in case the cornerback is beaten.
  • Running Back: The running back is handed the ball and has to run directly up the field through linemen and defensive backs.

This isn’t close to the full amount of positions that are called ‘skill positions’ but for the brevity of this article and the significance of the result it is necessary. For example, I could have looked at quarterbacks (who can often play until 40 years of age) but there are not enough of them playing in the league currently for there to be a significant sample size.

Age Distribution

First up, let’s graph the age distribution of wide receivers currently active in the NFL (this is their age on the 31st of December 2015, for those players that have their birthday between now and then, have a great day).

WR_n

This is a perfectly reasonable plot and should be expected. Players will get less athletic as they age, due to injuries or just wear and tear, and this should happen at a roughly constant rate. So it should be a smoothly declining graph, which is what we see here.

Now lets look at the age distribution for defensive backs.
DB_n

This is essentially the same graph again. A smoothish decline from the age of being drafted to older and older. Something cool that I missed out for simplicity is that there is currently a 39 year old defensive back in the NFL. Charles Woodson, free safety for the Oakland Raiders, is still one of the best in his position in the league. I thought it was worth a mention because its pretty damn amazing.

 

Now we can compare this with the age distribution for running backs in the NFL. 

 

RB_n

Up until age 30, this looks exactly like the others, a similar smooth decline. However, as soon as you get past age 30 the job prospects are terrible. There are more running backs of exactly age 30 (9) than running backs older than 30 (6). This implies there is a stigma attached to playing a running back over the age of 30 in the NFL.

Job Prospects

However, it is easy to see how the above analysis could be prone to biases. Perhaps it is just chance and better running backs just started being born after 1985. To try and get rid of this bias, I plotted a different statistic and asked the question “What percentage of players who were drafted and are now a certain age are still playing in the NFL?”. Simply: if you had all the players who had ever been drafted and were currently 25 years old in a room, what percentage of them are still getting paid by the NFL?

First up, wide receivers.

WR_prop

As you’d expect, most of the wide receivers who are drafted remain with the club for a few years, then as they age they generally are cut or retire. Again this seems like a smoothish curve which is what you’d expect from a distribution dominated by injuries and just general wear and tear.

Next, defensive backs.

DB_prop

One thing that is interesting – and to be expected – about the wide receivers but especially the defensive backs is that after a few years of being in the NFL there is a big drop (around 25%) in the proportion of players still employed. This is due to the rookie contracts ending (which are 3 or 4 years) and the team deciding not to sign them to a longer contract. After that point it is a fairly predictable gradient. Players get new longer contracts but gradually get injured or retire so the proportion gradually fades.

Now, the same graph for running backs.

RB_prop

Before 30, you see the same pattern. Three or four years of a rookie contract, followed by a steep loss, followed by a gradual loss. At age 30 the game changes entirely – so few of the drafted players have a contract after 30 that it looks like there’s a mistake on the plot. So even though running backs good enough to be drafted are of age 30+, very few of them still have jobs in the NFL.

Conclusion

There are plenty of reasons why running backs are hindered by their age. It is undoubtedly the most physically demanding skill position and this won’t change without a significant overhaul in the games’ rules. Also, there are a large amount of younger running backs looking to take their place and this won’t change without an overhaul in the league format.

The thing that I take from this is that running backs are treated as disposable by NFL teams, so much so that if they feel uncomfortable about your age they will drop you. If employment was simply a matter of their health and ability then you would see a gradual decline with age, instead it seems that teams are just subconsciously or consciously biased by the stigma of having a 30+ year old running back and would much rather go with the younger, cheaper – and potentially less talented – option.

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