From 2010-2012, it was tough to find a running back better in the stat sheets than Foster. He finished no worse than fourth in fantasy points at his position, and was a virtual lock to see plenty of touches. A back ailment cost him significant time in 2013, but he's returned to full strength heading into training camp and has no real backfield competition. If Foster regains his past statistical glory, fantasy owners will all be rewarded.

There are no guarantees that Ball will reach the potential so many analysts (including myself) see in him heading into this season, but he's still likely to cost fantasy fans one of their first two overall picks in drafts. Will he be worth it? Time will tell, but the past success of runners in a Peyton Manning offense is interesting, to say the least. Should Ball fail to become a star, however, it could be difficult for owners to overcome.

Which Martin will we see in 2014 -- the fantasy star of 2012, or last year's disappointment? New OC Jeff Tedford liked to use a featured back during his time at Cal, but he's also hinted at using a backfield committee in Tampa Bay. If Martin earns a prominent role, he's going to help countless owners win a league title. If he falters like he did before his shoulder ailment in 2013, the Boise State product could kill your chances.

At this point last year, no one argued that Spiller had first-round value. Heck, I saw him selected in the top five in some drafts ... yeah, that didn't work out so well. Here's the good news, though; Spiller is still a young runner with little wear and tear on him, and he'll be back at 100 percent from last season's troublesome ankle. If you can land him as a high-end flex starter, Spiller could turn into one of the year's top values.

Since 2000, a mere five rookie wide receivers (including Allen) have posted 1,000-plus yards. Of the first four on our list, three of them (Anquan Boldin, Marques Colston, A.J. Green) all went for 1,000 yards again the following season. Fantasy fans hope Allen joins this list and avoids being the next Michael Clayton. Any deviation from his upward-pointing statistical arrow would hurt many owners' chances at a fantasy league title.

Gronkowski (knee) appears to be on schedule for Week 1, but can he actually stay on the field? He's missed a combined 14 games over the last two years due to various ailments, all of which required surgical procedures (in some cases, multiple surgeries). Gronkowski will cost you a selection in one of the first five rounds, so he's one of the major risk-reward picks. He'll also be impossible to replace in a worst-case scenario.

Harvin was once considered a No. 1 fantasy wideout, and at 26 he's still in the prime of his career. Of course, he needs to stay on the football field to meet expectations. Since 2012, he's played in just 10 games due to various ailments. While he is expected to be fine for the start of camp, whether or not he remains healthy is a huge question. Should Harvin turn the clock back to his Minnesota days, he would become a bargain.

If you owned Brady last season, you know just how frustrating it was to start him on a regular basis. He finished 13th in fantasy points among quarterbacks, and his inconsistent level of play was enough to make fans pull their hair out. Brady's fate seems tied to that of Gronkowski, so this is a fantasy double whammy of sorts. With an ADP now in the middle to late rounds, Brady could be a real bargain ... or he could leave you bald.

Once considered a surefire top-five pick, Rice's stock is sinking faster than the Red Sox's chances of winning back-to-back World Series. Coming off a season with a dreadful 3.1 yards-per-carry average and staring a two-game suspension in the face, the Rutgers product isn't even guaranteed to keep his starting job. If he does see a rebirth under new offensive coordinator Gary Kubiak upon his return, however, Rice could have RB2 value for a flex-starter price.

Richardson has looked like two different players in his first two pro years. A top-10 fantasy runner as a rookie, the Alabama product rushed for two or fewer yards on almost 54 percent of his carries and finished 33rd in fantasy points among backs last season. Those are scary bad totals. If you're able to reduce risk and draft Richardson as a high flex starter, go for it. But taking him as a No. 2 runner before Round 6 is a big gamble.