By Scott Lindholm-

(CBS) In last night’s win against the Cowboys Matt Forte had 20 rushing attempts for 102 yards.

So what?

It’s a well-known fact that running backs hit a wall when they reach 30. This chart shows the number of running backs with at least one season gaining 800+ yards and at what age they played their last game:

(Table by Scott Lindholm)

(Table by Scott Lindholm)

There are 270 running backs since 1960 who meet this criteria and it shows the cruel fate all running backs face as they near 30—it’s less a gradual decline as much as a sudden drop-off in productivity that occurs for any number of reasons. Injuries, someone better or changes in the game make running back one of the positions with the shortest careers.

Forte turns 28 today, December 10th, so wish him a happy birthday at @mattforte22 if you’re so inclined, meaning he’s reaching that make-or-break stage every running back faces. But this chart doesn’t tell the entire story, since it’s not as much a running back’s age as his use that is the determining factor. This chart, using the same sample, shows the amount of yards gained after a running back’s 1500th career rushing attempt:

(Table by Scott Lindholm)

(Table by Scott Lindholm)

There are two important aspects of this chart:

  1. I chose an 800-yard season as a marker of running back because it implies he was an important cog in a team’s offense for at least one season. Of the 270 running backs in this sample, 66 (24.4%) had a career as long as Forte. Given historical trends, he’s already playing on borrowed time.
  2. Time isn’t kind to the running back. Of these 66, 23 gained less than 1000 yards in the rest of their careers after their 1500th rushing attempt, another 12 less than 2000 yards. 35 of these 66 running backs (53.0%) were pretty much at the end of their careers, and certainly at the end of the productive phase of it.

And after last night’s game, Forte has—1,496 carries in his career.

This sample does NOT include active players like Forte—others still playing with 1500+ career rushing attempts are Frank Gore, Steven Jackson, Chris Johnson, Maurice Jones-Drew, Marshawn Lynch, Willis McGahee and Adrian Peterson.

Interestingly enough, all but McGahee are in the top 10 in rushing yards this year and there’s no doubt modern training and surgical practices have extended the careers of running backs, but these players would be wise to ask not for whom the bell tolls. AP’s injury on Sunday shows how quickly a running back’s situation can change.

Amassing significant yardage as a running back requires two things, ability and luck, since the annals of football are littered with stellar backs who were injured and a ghost of their former selves upon their return like Billy Sims and Terrell Davis or simply run into the ground like Michael Turner. It’s a fate that awaits them all, and the ones on the right side of the chart end up being enshrined in the NFL Hall of Fame not just because they were outstanding but because they defied the odds and stayed healthy into their 30s.

Luckily for the Bears, rushing talent is relatively easy to obtain—of the top 20 rushers this year only eight were first round picks. Of those only three (Reggie Bush, AP and C.J. Spiller) were top 10 picks, and two (Benjarvus Green-Ellis and Fred Jackson) were undrafted. Rushing talent can be found, and if trends are to be believed, the Bears may be in the market for a new running back sooner rather than later.

Scott Lindholm is a columnist for and and frequent contributor to The Boers and Bernstein Show, known affectionately as Scott from Davenport. You can follow him on Twitter @ScottLindholm.