What Is The Length Of An NFL Running Back’s Career?

May 16, 2012

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How long can Trent Richardson expect to play in the NFL?

The topic comes up every year: how long is the average football player’s career?  People are particularly interested in the length of an NFL running back’s career, since it seems that injuries often cut their careers short.  This is often given as 4-5 years, with some estimates coming in as low as 2.5 years.

As is often the case, methodology is going to be very important.

Perhaps the worst methodology I have ever seen was looking at the current starting running backs and calculating the mean number of years they have been in the NFL.  However, this uses mid-career numbers and is going to underestimate the reality.  Would you take a 2 year old, 45 year old, and 75 year old and simply use the mean of their ages (40.67) and declare this to be the average life span?  Of course not – nor should you use mid-career numbers to calculate the average length of career.

The second issue is the decision of whom to include.  Do we include ALL NFL running backs, even the guy from Kosmo State who went in the 7th round and narrowly held onto a roster spot for a year before getting cut?  This guy’s career was cut short by lack of talent, not by injury.  We need to separate the wheat from the chaff and determine the average career length of a GOOD NFL running back.  I doubt that the casual fan is too concerned about how long her team’s third string back will kick around the league.

My methodology

There are two decisions to be made with the data.  The first is how to quantify “good”.  I’m going to take the years 1991-2010 and look at running backs who finished in the top 20 in the league in rushing yards at least once during that twenty year span.  My thought is that if you’re a good running back – the type that carries a team – you’re going to land in the top 20 at some point.  Maybe not every year, but at least once.  This is going to miss some situations like guys who are part of a tandem backfield for their entire career, but it should at least provide a decent sample size to work with.  I am excluding active players (defined as players who played in 2011), because of the problem with mid-career numbers.  Rushing yards isn’t a perfect barometer, but it should be fairly sound.

The second decision is what is meant by “length of career”.  Years can be messy – if a guy plays 9 games, does he get credit for a year?  I decided to just scrap the idea of years and go with games instead.

The data

Twenty years of top 20 lists means 400 names.  However, many players made the list multiple times.  There were 150 unique names on the list.  40 of these players are active, leaving 110 retired players in this group.  Here is the list, in order of most to fewest games played.

Player Games
Emmitt Smith 226
Marcus Allen 222
Earnest Byner 211
Jerome Bettis 192
Herschel Walker 187
Thurman Thomas 182
Warrick Dunn 181
Marshall Faulk 176
Curtis Martin 168
Chris Warren 162
Anthony Johnson 159
Mike Alstott 158
Tiki Barber 154
Troy Hambrick 154
Barry Sanders 153
Fred Lane 153
Michael Pittman 151
Corey Dillon 150
Craig Heyward 149
John L. Williams 149
Ahman Green 148
Edgerrin James 148
Charlie Garner 147
Eric Dickerson 146
Dorsey Levens 144
Leroy Hoard 144
Ricky Watters 144
Stephen Davis 143
Eddie George 141
Bernie Parmalee 134
Antowain Smith 131
Jamal Lewis 131
Terry Allen 130
Fred Taylor 126
Garrison Hearst 126
Harold Green 124
Tyrone Wheatley 124
Shaun Alexander 123
Adrian Murrell 122
Brian Westbrook 121
Neal Anderson 116
Lamar Smith 115
Duce Staley 114
LaMont Jordan 114
Reuben Droughns 114
Clinton Portis 113
Priest Holmes 113
Edgar Bennett 112
Ladell Betts 111
Harvey Williams 110
Lewis Tillman 109
Lorenzo White 107
Michael Bennett 107
Marion Butts 104
Rodney Hampton 104
Erric Pegram 103
Rodney Thomas 103
James Stewart 101
Dominic Rhodes 99
Gary Brown 99
Kevin Mack 99
Earnest Graham 98
Mario Bates 98
Mike Anderson 98
Robert Smith 98
Deuce McAllister 97
Rudi Johnson 95
Brad Baxter 94
Julius Jones 94
Justin Fargas 92
Reggie Cobb 92
Napoleon Kaufman 91
Mark Higgs 90
Travis Henry 89
Jamal Anderson 88
Natrone Means 88
Robert Delpino 88
Allen Pinkett 87
Anthony Thomas 87
Errict Rhett 86
Leonard Russell 85
Kevan Barlow 84
Rod Bernstine 84
Leroy Thompson 80
Willie Parker 79
Christian Okoye 79
Terrell Davis 78
Ronald Moore 77
Bam Morris 74
Johnny Johnson 72
Roosevelt Potts 71
Chris Brown 68
Cleveland Gary 68
James Allen 66
Blair Thomas 64
Kevin Jones 64
Barry Foster 62
Jerome Harrison 62
Abdul-Karim al-Jabbar 61
Gaston Green 58
Stacey Mack 58
Derek Brown 56
Raymont Harris 54
Tatum Bell 54
Olandis Gary 48
Domanick Williams 40
Reggie Brooks 40
Curtis Enis 36
Rashaan Salaam 33
Robert Edwards 28
Total  12034


Mean: 109.4

Median: 103.5

If we divide these numbers by a 16 game schedule, we get 6.8 years for the mean and 6.5 for the median.  However, it’s important to note that it’s pretty common for a player – in any sport – to get dinged up and miss a game every one in a while.  So even a generally healthy running back would generally stretch these games out over 7.5 – 8 years.  Only 27 of the 110 players in the group had a career of 80 games or fewer (5 full seasons).

Most likely, a running back with Trent Richardson’s pedigree can bank on an eight year NFL career.  Longer if he’s lucky, shorter if he’s not.

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10 Comments (+add yours?)

  1. Lazy Man and Money
    May 25, 2012 @ 00:00:46

    This is solid analysis. One thing that I noticed in looking at the data is that the guys at the top seem to be players who are from an older time

    For example, Walker, Byner, Thomas, Dickerson, Barry Sanders are guys that I associate with the 80-90s. When I look at the players that I think of from the 2000’s era, the names that come to mind are Alexander, Westbrook, Fred Taylor, Clinton Portis, Edgerrin James.

    The lack of players who retired in the last 5 years with 150 games played, or even 130 games, is interesting to me.

    I could only find one Fred Lane (http://www.pro-football-reference.com/players/L/LaneFr00.htm) who had 42 games not 153.


  2. kosmo
    May 25, 2012 @ 08:14:10

    Hmm. The Fred in the list should be Fred Taylor. There is a Fred Lane, but he wouldn’t have made the sample, due to falling short of the top 20. 153 is the correct number of games for Taylor.

    Guys from the list with 150+ games who retired later than the 2005 season

    Jerome Bettis ( last year played 2005)
    Warrick Dunn (2008)
    Marshall Faulk (2005)
    Curtis Martin (2005)
    Mike Alstott (2006)
    Tiki Barber (2006)
    Corey Dillon (2006)
    Fred Taylor (2010)
    Michael Pittman (2008)

    There were 18 players with 150+ games, and this is 9 of them. That’s a healthy portion. If you draw a line in the sand and look for guys who retired later than May 25, 2007, you’d only get three (possibly more, if some of the guys who last played in 2006 showed up at camp in 2007). You’d expect about 4.5, but this is a fairly small sample size to work with, though, and seems to be affected by the fact that there was a big bubble of retirements in 2005/2006, with 6. The 150 cutoff also narrowly misses Ahman Green (148, last played in 2009) and Edgerrin James (148, 2009).

    So if you set the retirement date as 1/1/2007 (5.5 years ago) or later you’d get 7 players, which is about what you’d expect statistically. If you keep the date at a hard “within the past five years” but push down to 145 games, you’d get 5, which is about what you’d expect. I suspect random variation is the primary cause.

    What will the future hold? Let’s look at these active (as of the 2011 season) players with 100+ games. It’s not a good idea to try to project career lengths mid-career, but it seems reasonable that quite a few of these guys will hit 150+ games.

    Thomas Jones – 180 games
    LaDainian Tomlinson – 170 games
    Kevin Faulk – 161
    Chester Taylor – 151
    Ricky Williams – 147 games (not including 3 lost seasons)
    Maurice Maurice – 145
    Sammy Morris – 144
    Willis McGahee – 120
    Michael Turner – 118
    Steve Jackson – 115
    Frank Gore – 100


  3. Lazy Man and Money
    May 25, 2012 @ 09:43:02

    You had Fred Taylor in the list at 126, so I thought that was accurate ;-).

    I recognized that a number of 150+ gamers retired by 2006, but it seemed odd that there were none from 2007, 2 from 2008, none in 2009 and one in 2010. My point here is that these were the 150+ gamers, and these are rare. While the 150 cut off narrowly misses a few guys… a 160 cut off seems to cut more of them (Taylor, Pittman, Alstott, Dillon). As you go up toward the top of the list, I see guys who played in the 90’s more, which is the point that I was trying to make.

    As for what the future holds, I think the game has changed to make much of this analysis not particular useful.

    As a Patriots fan, two of the names jumped out on the list: Kevin Faulk and Sammy Morris. Kevin Faulk might have 160+ games played, but he has 864 rushing attempts. That’s 5.36 attempts per game. Compare that to Emmit Smith at the top of the list who has 19.51 attempts per game. Sammy Morris has a similar story with a 5.11 attempts per game. Morris for the Patriots in some years was mostly a special teams player. The year he got a lot of carries was due to injury to Lawrence Maroney. It would be hard to classify such players are full-time RBs.

    I don’t know if I consider Faulk or Morris’ 140-160 games noteworthy when it takes them 3-4 games to carry the ball as much as Ray Rice or Adrian Peterson.

    Teams are splitting running back duties more and more, which is causing some difficulty for those in fantasy leagues. Games played is meaning less and less for RBs in today’s NFL than it used to.

    For the same reasons why you have to take the games played and divide them into seasons, you have to take the rushing the attempts and quantify those what an average should be for a full-timer.

    However, if you do that, are you really answering the question of average length in the NFL? If we are talking in terms of years being paid, I don’t think we are. Morris and Faulk got paid for a number of years. Of course, they were paid proportionate for the amount of work (not getting Peterson or Rice contracts). However, if we are talking about how much wear and tear a RB typically takes before retiring, I think the average number of rushing attempts is valuable. (Fortunately, Pro-Football Reference provides this number for the career quite easily – no math necessary).

    In my mind there’s little doubt that the contact of running the ball 18-20 carries a game is a lot more damaging on the player than say a wide-receiver who might catch 5-6 balls a game. It’s far fewer tackles to take and far less contact in general.


  4. kosmo
    May 25, 2012 @ 10:20:28

    The Fred Taylor 126 is definitely wrong. 153 is the right number. I’m not exactly sure who the 126 belongs to.

    There are 18 total 150+ guys in the list, so it’s rare to reach this level in general. So it’s not surprising that it’s also rare from guys who played in the 2000s to not be in the 150+ group. The oldest guys on these top 20 lists (Dickerson, Allen, Herschel, etc) would have entered the NFL in the early 1980s. So, realistically, you’re comparing guys who were stars in the 1980s AND 1990s to guy who were stars in the EARLY 2000s. Guys who were stars in the late 2000s aren’t on the list because many of them are still active.

    Also, you can’t be a 2004 draftee (for example) and have 150+ games played. It’s simply not mathematically possible. It’s going to take some time for some of the guys you think of as studs from the 2000s (Adrian Peterson, Chris Johnson, Arian Foster) to get to 150 games.

    I think we’re going to see another bubble of 150+ retirees in 2013-2016.

    Morris and Faulk would probably fail the “top 20” aspect of my sample. I just grabbed the top RBs by games played, in an effort to save time 🙂

    The main purposes was for me to debunk the “fact” than a running back only plays 2.5 – 4.5 years.


  5. Lazy Man and Money
    May 25, 2012 @ 11:06:15

    I know I was comparing guys from the 1980s and 1990s to early 2000s. It seems like in general those 80s-90s guys are higher up on the list. Perhaps I should gone with the 160+ games rather than the 180+ to make it more clear that only 2 of the 7 didn’t play in that late 80s-early 90s era.

    It seems interesting to me that more players from recent years aren’t getting to the 150+ or 180+ game mark. What happened to Priest Holmes and Shaun Alexander to stop them? Brian Westbrook had concussions I think, which was a direct result of the danger at the position. What stopped Clinton Portis from getting to 150 games? Deuce McAllister, Jamal Lewis fall in the same category as recent players who couldn’t get there. It seems like these are the guys who should have retired recently or would have been retiring with 150+ games.

    I realize that we can’t look at guys like Peterson, Rice, Foster, etc., but in looking at the guys that mentioned above, I would put many of those guys in the same group – especially Portis, Holmes and Lewis. Those guys either lead the league in rushing in one year (Holmes and Lewis) or had multiple 1500 yard seasons (Portis). Those three seemed to hit 120 games or the 7.5-8 average that is the norm. I guess my point is that with these guys, don’t expect to see 150 or 180 games unless they become part of a platoon.

    I think when people make the point that a RB plays only 2.5 – 4.5 years, they are essentially stressing it is a short career. You can strip out the failures in any sport and make it longer. In this case even the 7-8 season average of very good players seems to be small. I don’t think it compares well to baseball players once you strip out the failures there. You take someone with a small frame like Pedro Martinez and he had 409 starts. With an average of 31 starts a season, he would play 13 years – almost double the length of the NFL RBs career.

    Maybe it is easier to just group all the wheat and chaff together for purposes of a sound bite.

    If feels to me like the average for the 80-90s guys might be higher than the average than the 2000s guys. If I had motivation, I would like to attempt to divide this list and quantify that.


  6. kosmo
    May 25, 2012 @ 11:25:18

    When I heard the 2.5 or 4.5 number, it seems like it’s often being used to help a “wheat” player get a better contract. Agent says “Stud Tailback should get a huge deal because the average career length is 4.5 years.”

    I have no problems including some guys who failed (Curtis Enis) … but not guys who had a 99% chance ot failure from day one. When you include Mr Irrelevant, you’re muddying the data beyond the possibility of any analysis. I think casual fans want to know how long the guys from the top few rounds can expect to play – not so much the 7th rounders and undrafted free agents.

    Any chance that recency is causing you to remember 2000s flameouts and not the guys from the 80s and 90s? Here are a few to get the ball rolling.

    Billy Sims. Seasons of 1303, 1437, 1040 yards. 60 career games
    Craig James, 1227 yards in 1985. 52 career games.
    Reuben Mayes. 1353 in 1986, 917 in 1987. 76 career games.
    George Rogers. Seasons of 1674, 1144, 1093, 1203. 92 career games.

    Is Billy Sims the 1980s version of Priest Holmes?


  7. Lazy Man and Money
    May 25, 2012 @ 12:40:48

    It is quite possible that recency would cause me to remember the 2000 flameouts. Other than the Super Bowl 20, I didn’t really follow football until 1987 or so. The only one of Sims, James, Mayes, and Rogers that I recognize is James, probably because he was in that Super Bowl and in my local (Boston) newspapers. I don’t think the Patriots played too many against the Saints’ Mayes and I didn’t have an Internet connection or a web to read about him.

    Sims had a bad knee injury which I think is the part of the point of highlighting the short career of running backs. From the beginning of my era, the “Sims” is Robert Edwards – a knee injury essentially ending his career. I do remember them. I think Priest Holmes played a lot more games, before having his Sims or Edwards moment, though it was a neck injury for him.

    Are there more injuries ending RB careers early now than before? I’m not sure, but that would be interesting to look at. I bet you could statistically look at players’ combine results and see that they are bigger, stronger, and faster than before. Do their knee ligaments get proportionally stronger to help with these collisions? My initial thought is not likely However, maybe improvements in equipment (better pads and braces) help.

    I have to laugh at agents saying that a stud RB, should get a huge deal due to the 4.5 year career. If that were true, it would be the big reason NOT to give them a huge deal. The rookie deal is 4 years now (I think there’s a provision for a 5th year with the team option). So by the time the RB would be up for a new contract, he’d be ready to leave the game if that average were true. Hard to push for a big contract when you are that “old.” I’m sure the agent saying that in the negotiating room isn’t going to get too many clients big pay days.


  8. kosmo
    May 25, 2012 @ 13:08:27

    I think you mean Super Bowl XX.

    Maybe it’s more the players themselves than the agents (and probably media reaction). I’m thinking of holdouts situations over the years. Blah blah need to maximize blah blah average career lasts 4 years blah blah.

    The knee injuries – like Sims and Edwards – are something I wanted to account for in my sample. That’s why I made the “wheat” bar fairly easy to reach – just hitting the top 20 in yards at least once. I just wanted to exclude guys who rushed for 88 yards in 10 career games. My goal was to point out that while there are guys like Edwards, Curtis Enis, and Rashaan Salaam, there are also guy like Marshall Faulk, who tallied 176 games while being involved in seemingly every offensive play – and playing a huge number of games on turf.


  9. Lazy Man and Money
    May 25, 2012 @ 13:19:56

    The Romans lost their empire long ago.

    I’m sure it is about the players themselves saying that they need to maximize their time. Still, they have to be careful, because they could do more harm than good.

    I think you did a lot of great stuff here. I wonder how it will translate to the changes towards platoons going forward. They may hit that top 20 mark, but be getting 25-50% less attempts than RBs in the past.


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