With only three games left in the season and playoff spots starting to disappear, several teams gunning for postseason success face some serious questions concerning their running game over the next few weeks.
Some are in a far more comfortable position than others. Running backs have always fit seamlessly into Bill Belichick's systems in New England.
Forever playing second fiddle to Tom Brady and the Patriots passing game, a productive running game was always an added bonus for the Patriots.
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The Cincinnati Bengals have the luxury of two backs playing at a solid level, albeit their production has been somewhat inconsistent at times.
Jeremy Hill and Giovanni Bernard have shared the load in Cincinnati successfully. Meanwhile in Denver, the benching of Peyton Manning has put more responsibility on C.J. Anderson and Ronnie Hillman's shoulders.
In the NFC, Jonathan Stewart has been chugging along consistently as a support player to the Cam Newton inspired offense for the Panthers, whilst Peterson has placed the Vikings offense squarely on his shoulders as normal.
It hasn't been quite so comfortable for several other teams, however.
Now assured a playoff berth, Arizona face some serious problems with their running game going forward. With both Chris Johnson and Andre Ellington out, rookie David Johnson now carries the Cardinals run game by himself.
In Seattle, the injuries to Marshawn Lynch and his replacement Thomas Rawls has left a gaping hole in the Seahawks offense, which had already lost playmaker tight end Jimmy Graham for the year.
Running out of weapons quickly, Seattle needs to find other options for Wilson to keep opposition defenses guessing.
These NFC teams have the luxury of falling back on a relatively established quarterback. In the AFC, teams with running back issues are in a bit more of a problem.
The Colts, in a dogfight with Houston for top spot in the NFC South, have been successful under interim quarterback Matt Schaub with the ageless Frank Gore at running back. Whether the former 49ers workhorse has the gas in the tank to carry the team to the playoffs is debatable.
The Chiefs, Steelers and Texans have lost their marquee backs to season-ending injuries. Fortunately, their replacements have slotted into their systems remarkably well. Perhaps the surprise in this season of back-up running backs, Charcandrick West fit seamlessly in for the injured Jamaal Charles at Kansas City.
Now seemingly recovered from a hamstring injury, the Chiefs may rely more and more on the improving play of the young back.
Having lost Arian Foster for the year, the Texans returned to Alfred Blue who had filled in for the perennially injured Foster at the start of the season. Blue has struggled to fill the demands of a feature back role like Foster but, like the situation in Kansas, the Texans have benefited from the stability and consistency brought by Hoyer to their quarterback position.
Perhaps most damaging of all was the Steelers' loss of star running back Le'Veon Bell. DeAngelo Williams has slotted in well but really it has been the play of Ben Roethlisberger and his receiving corps which has kept the Steelers alive in the playoff run.
The question facing the teams which have lost their feature back is whether their quarterbacks are capable of carrying their offenses through to the playoffs.
For some of these quarterbacks, the pressure will be no problem (Roethlisberger, Palmer and Wilson for instance). For others, this situation brings a whole new level of pressure to their game.
If Hoyer, Smith and Schaub can keep their heads over the next few weeks, their teams will find themselves contending for a coveted playoff berth.
The loss of these star running backs hurts these teams but for now, the back-ups are performing well and doing enough to keep their teams' post-season hopes alive.