DeMarco Murray led the league in rushing last year, and he may be headed for free agency. Both he and Dez Bryant are due to be free agents, and the Cowboys might not be able to afford to re-sign both of them. And should Dallas even try to re-sign Murray.

Murray stayed healthy last year, but he has an extensive history of injuries, dating back to his days at Oklahoma, and the attrition rate tends to be pretty high with heavily used running backs anyway.

In the last 20 years, 34 running backs have carried the ball at least 350 times in a season. Almost half of those running backs (16) had at least 60 fewer carries the next season.

Only five of those heavily used running backs had EVEN MORE carries the next year. Only six finished with more yards, and only seven scored more touchdowns. Over two thirds of said running backs (25) averaged more yards per carry.

NFL teams and fantasy GMs should be aware that it’s tough staying on top at the running back position.

Here are those 34 running backs, with their rushing stats for the season after they carried the ball over 350 times.

RUNNING BACKS WITH 350-PLUS CARRIES (the next year)
YearPlayer AttYards AvgTD
1995Emmitt Smith37717734.7025
1996Curtis Martin31611523.6514
1996Emmitt Smith32712043.6812
1997Ricky Watters28511103.907
1998Terrell Davis39220085.1021
1998Eddie George34812943.705
1998Jerome Bettis31611853.803
1999Curtis Martin36714644.005
1999Jamal Anderson19593.100
1999Terrell Davis672113.102
2000Curtis Martin31612043.809
2000Edgerrin James38717094.4013
2001Jerome Bettis22510724.804
2001Eddie George3159393.005
2001Edgerrin James1516624.403
2002Stephen Davis2078204.007
2003LaDainian Tomlinson31316455.2513
2003Ricky Williams39213723.509
2004Deuce McAllister26910743.999
2004Jamal Lewis23510064.287
2004Ahman Green25911634.497
2004Ricky Williams00.000
2005Shaun Alexander37018805.1027
2005Rudi Johnson33714584.3012
2005Curtis Martin2207353.305
2006Tiki Barber32716625.105
2006Clinton Portis1275234.107
2006Edgerrin James33711593.406
2006Shaun Alexander2528963.607
2007Larry Johnson1585593.503
2009Adrian Peterson31413834.4018
2009Michael Turner1788714.9010
2010Chris Johnson31613644.3011
2013Arian Foster1215424.471
2015DeMarco Murray????

—Ian Allan