Running back is one of the hardest positions to find value in in all of fantasy football. Generally speaking, getting an RB1 at the top of the third round would usually be considered a steal. You simply can't say the same about any other position. In order for a running back to be considered a sleeper, they've got to have a few things going for them: talent, touches, and a successful offense around them.
Devonta Freeman, RB Atlanta Falcons
Freeman was drafted in the fourth round of the 2014 draft. A bruiser of a back, he showed off some great power in big games in his final year in college, specifically during the BCS championship game. He also has the ability to play a role in the passing game, something the Falcons could very well take advantage of.
All OTA, minicamp and training camp reports have said that Freeman has been consistently impressing coaches and the media. I'm more than willing to buy into the hype of Freeman, who draws comparisons to players like Ahmad Bradshaw and is sitting behind the 31 year old Steven Jackson. If Jackson, who has already showed signs of slowing, misses any more playing time Freeman will be there to make the most of the opportunity, and will likely hold onto the job from there on out.
I expect Freeman to take the starter role away from Steven Jackson by mid-season, if not earlier depending on when Jackson gets hurt. He's being drafted on average at the top of the 10th round. I would be willing to get bullish and take him in the 9th.
Lance Dunbar, RB Dallas Cowboys
Last season current Cowboys offensive coordinator Scott Linehan was calling plays in Detriot, where he had both Reggie Bush and Joique Bell churning out yardage and points. Bush and Bell would finish as 11th and 17th among running backs, respectively.
Dunbar, like Bell, possesses great pass-catching abilities and has some scary open field potential. Unlike Bell though, Dunbar sits behind Demarco Murray, a player who has proven himself to have a difficult time staying healthy for an entire season. One injury would set him up for a lot of fantasy potential, especially after factoring in that Dallas has reinvented their offensive line with the additions of last year's first rounder C Travis Frederik (already amongst the league's best in run-blocking) and this year's first rounder RG Zack Martin.
Dunbar comes with some risk though, as last season he found himself finishing the season on Injured Reserve after having what looked to be a breakout game against the Oakland Raiders (where he had 12 carries for 82 yards and one catch for 12). Dunbar is going in the 13th round on average. I'd confidently draft him at that position.
Chris Ivory, RB New York Jets
When looking at the average draft position for running backs, one name that stuck out to me was Chris Ivory, who's being drafted as late as the 11th round. Last year Ivory was being drafted in the 3rd round of most drafts, and while he didn't produce as much on the field as most people thought he would, when he was active he was an unstoppable force.
According to PFF, Ivory finished as the 3rd most elusive back last season behind only Adrian Peterson and Lesean McCoy--that's some pretty elite company. With the addition of Chris Johnson to the Jets backfield, Ivory's stock has plummeted into an area where veteran running backs' careers usually go to die.
Chris Johnson, however, is more of a threat to steal passing snaps from Ivory rather than running snaps. Chris Johnson is very good at putting quarterbacks in compromising 3rd and longs. Not to mention, CJ2K isn't even close to the goal line back Chris Ivory is. Ivory's main concern is his ability to stay healthy, but at the cost of an 11th rounder the upside is well worth the risk. I'd be willing to draft Ivory as early as the 9th round.
Shonn Greene, RB Tennessee Titans
Okay, Shonn Greene is by far the least exciting player in this group. But, he has to be mentioned because of the position he's in. Current Titans coach Ken Whisenhunt used to be the head coach of the Arizona Cardinals, where he famously didn't allow rookies significant playing time.
Even after drafting Beanie Wells first overall, he forced him to split time with Tim Hightower. Yes, one of the most electrifying college backs was in a nearly 50/50 carry split with one of the least exciting running backs in the NFL. Now, Bishop Sankey has joined the Titans offense, and history would suggest that Shonn Greene will still remain relevant this season as a result of Whisenhunt's tendencies.
Greene was unexciting in the New York Jets offense, consistently being carried by his offensive line and plodding his way to any yards he did accrue. That won't stop him from potentially playing up to a low end RB2 if the 50/50 split continues all season. He's being undrafted in 12 man leagues on average, so he could be grabbed in the final round of your draft. I'd recommend picking him up on the waiver wire as soon as one of your players succumbs to injury or proves ineffective.