Every year things like injuries, coaching changes, scheme switches and a host of other factors play a big role in the success of running backs.  Something as small as a change in blocking scheme or the loss of a lineman can really impact a running back’s ability to perform at the highest level right out of the gate. 

So far this offseason and preseason, we’ve seen a ton of these scenarios play out already and effect a number of teams.  As fantasy owners, these are the top-five running backs you should be most wary of getting off to a slow start for the 2013 season. 

5.  Arian Foster - Houston Texans

Foster is battling back and leg problems, keeping him out of preseason action (like always).  While he rehabs and prepares to return week one, Ben Tate will get to showcase his talents and make a case for an increased role in the Texans’ offense.  Tate started Houston’s game against the New Orleans Saints this past Sunday and ran for an impressive 67 yards on 11 carries (6.7 YPC) and a touchdown.  Tate looked electric in his time on the field and if he turns in another strong performance like this in the final preseason game, he will put Houston in a difficult situation. 

With Foster coming back from injury and Tate playing impressively, the Texans’ coaching staff could look to ease Foster back into action and give Tate more carries than usual for the first few games.  If this is the case, or Foster still isn’t 100 percent, look for his fantasy value to take a bit of a hit in the first few weeks.  Don’t worry too much though, he’ll eventually get going and still put up top-10 numbers as long as he can stay on the field. 

4.  Eddie Lacy - Green Bay Packers

Lacy has been inconsistent so far this preseason.  After missing the first game, the Rookie has compiled 35 yards on 16 carries (2.2 avg YPC) and no touchdowns.  He also has only one catch for 11 yards in two games. 

While you can’t look at preseason stats too closely and must take them with a grain of salt, it is something to be cautious of.  Lacy did not look good when matched up against a top defense like Seattle’s.  Fantasy owners also must worry about the state of Green Bay’s offensive line, as well as how little is still known about how Mike McCarthy will utilize Lacy in the offense. 

If the Packers figure everything out, this shouldn’t be a problem.  But as of right now, it appears as if Lacy could come out of the gate a lot slower than everyone is expecting. 

3.  Ronnie Hillman, Montee Ball and Knowshon Moreno - Denver Broncos

Yes, technically this is three different guys, but from a fantasy perspective, their fates are closely tied together.  All three have spent time this offseason as “the guy” and seen their ADP and fantasy value skyrocket for a short period of time. 

Jon Fox has a history of misusing running backs and overusing large committees, there’s no telling what these guys will give you from a fantasy perspective this season.  Until things get underway in Denver and we get a better picture of how the Broncos will handle running the ball, it’s very likely all three of these guys won’t make the biggest fantasy impact to start the season. Hopefully it will be short lived, but there’s a chance this could be an ongoing problem throughout the season. 

2.  Darren McFadden - Oakland Raiders

Sometimes it really feels like McFadden has been in the NFL forever and should be pushing 30 by now, but he’s actually only 25 years old as he enters his sixth season in the league.  McFadden has battled injuries throughout his career, having never played in more than 13 games in his first five seasons.  Once again, he’s already battling a shoulder injury and the season hasn’t even started yet. 

Raiders’ head coach, Dennis Allen, has publicly announced that McFadden will be ready to go for Week 1, without question.  The problem here is that by now it is painfully obvious that McFadden is extremely fragile, despite his plethora of talent.  Couple that with the fact that Oakland’s offensive line is now in shambles with the loss of franchise left tackle Jared Veldheer, and this could spell disaster for McFadden. 

Even if Run DMC can stay healthy, it will not be smooth sailing by any means, especially at the start of the season as the Raiders look to adjust to a shuffled and less-talented offensive line, which definitely points to a slip in fantasy numbers. 

1.  Rashard Mendenhall - Arizona Cardinals

Mendenhall is currently dealing with a sprained knee and is listed as day-to-day, but head coach Bruce Arians says that they’re hopeful Mendenhall will be able to go in Week 1.  Even if this is indeed the case, Mendenhall will likely not be 100 percent until Week 2 or 3 at the earliest. 

The biggest factor here is the loss of rookie guard Johnathan Cooper for the year to a broken leg.  Cooper was the Cardinals first-round pick and the seventh overall and was being counted on as the lynchpin to this offensive line and specifically the running game with his athletic ability to get downfield.  Now armed with a much less talented offensive line and a bulky knee, Mendenhall won’t come close to his career average of 4.1 YPC.  Out of all of the ‘backs on this list, Mendenhall is the clear lock for a slow start.  Buyers beware.