I can't promise you that Adrian Peterson will be the NFL's MVP again in 2013. I can't promise that he'll threaten Eric Dickerson's all-time single-season rushing record again. And I can't promise that he'll finish as fantasy football's most valuable draftee again. But if you have the No. 1 overall pick in your league this year, Peterson is your choice. There's no controversy there.

That said, there might be more uncertainty in the rest of the fantasy world heading into '13 than I can ever remember. How many running backs do you think are "safe"? How many tight ends? Which quarterbacks will emerge from a giant upper echelon and become truly elite? Yes, selecting AP for your team makes things easy. But after that, we'll all have a whale of a time predicting the near football future.

With that in mind, let's look at 10 players who embody this uncertainty in '13, the guys about whom opinions will vary wildly and who could cause fantasy squads to soar or crater. My ranks for the upcoming season will sink or swim in great measure based on how accurately I've got these 10 guys pegged.

Coming off such a major injury, will Robert Griffin III carry the ball 120 times again in 2013? Geoff Burke/USA TODAY Sports

Robert Griffin III, QB, Washington Redskins: It sounds more and more like RGIII will play Week 1, despite tearing his right ACL on Jan. 6. If he's free and clear of all knee woes and allowed to play instinctively, I've got him ranked way too low at No. 9 among fantasy QBs. Heck, his 815 rushing yards last year were fifth-most in a single season by a signal-caller. As I discussed at length in my piece about running QBs, all RGIII has to do is maintain decent production as a thrower and he'd easily fit inside the top five fantasy QBs, provided his running stays strong. But that's the question, right? Even if he's ready to go on Sept. 9, will he be as willing to scramble? And will the knee hold up just nine months after the catastrophe?

Andrew Luck, QB, Indianapolis Colts: Luck finished No. 9 among fantasy QBs last season, yet I've got him No. 12 for his sophomore campaign, and unlike RGIII, Luck isn't coming off surgery. There's every reason to believe Luck will improve in his sophomore campaign; I expect his completion percentage to be much better than 54.1 percent, and I expect he throws significantly fewer than 18 interceptions. To some extent, Luck is a victim of a numbers game: There are just a lot of really good QBs. I don't think there's much space at all between Matthew Stafford at 10, Tony Romo at 11 and Luck at 12. If there's a tiebreaker among those guys, it's concern over a changing Colts offense. Luck's collegiate offensive coordinator, Pep Hamilton, will call plays in Indy this season, and while the big-armed Luck will always be a good bet to take some chances down the field, I expect Hamilton to focus on lower-risk, lower-reward, longer-drive play calling. Luck's efficiency will go up as a result. But his fantasy stats may plateau.

Steven Jackson, RB, Atlanta Falcons: My Twitter feed saw more action this spring over my ranking of Jackson than perhaps any other player. Jackson's doubters are worried that he turns 30 in July, that the Falcons are a pass-oriented offense, that Jacquizz Rodgers will take away a big chunk of the backfield workload, and that Jackson just isn't all that good. On that final point, I beg to differ. I have Jackson ranked No. 11 among RBs, and I think there's a chance that's not high enough. Look at where Jackson finished among fantasy RBs in each of his eight seasons as a starter with the Rams:

Consider that the Rams went 36-91-1 over this span, never posted a winning record, and lost 10-plus games five times. These were not good teams. It's obvious that the '13 Falcons will be Jackson's best squad, plus it's a team that made Michael Turner a usable fantasy player over the past two seasons (21 combined TDs) despite his obvious decline. Think of it this way: In the past three years, Jackson had 43 carries inside an opponent's 10. In that same span, Turner had 102. With a bad team, Jackson's downside has been a solid No. 2 fantasy RB. With a good one, a No. 11 ranking seems modest to me.

Maurice Jones-Drew, RB, Jacksonville Jaguars: I have MJD 15th among RBs, but I don't feel right about it. I wish I could've gone higher. One of my favorite players and an incredibly effective runner despite his 5-foot-7 stature, Jones-Drew is recovering from Lisfranc surgery and is considered questionable for the start of training camp. Plus, the Jaguars have changed over to a zone-blocking scheme with which MJD isn't familiar, and they brought in Justin Forsett -- who played in a zone system last year in Houston -- to be the backup. Add the continuing mess at QB, and MJD doesn't look primed for a re-breakout. But skills are what matter, and Pocket Hercules has skills in abundance. Jones-Drew is a goal-line beast, has deceptive speed, is amazingly quick, can catch it and can pass protect. Plus, he's entering a contract year after last season's bitter summer holdout. I wrote last year that MJD has a chance to make the Hall of Fame, and while losing 10 games to injury last season throws a wrench into that conversation, it's still possible (though he'll have to remain a very effective player into his 30s). I'll need to see him run in preseason game action before I can say for sure, but Jones-Drew is a candidate to seriously outperform his rank.

Chris Ivory, RB, New York Jets: There's enough reason to doubt Ivory that I couldn't put him into my top 20 RBs (he's 21st). Even in an ancillary role with the Saints over the past three seasons, he suffered knee, hamstring, foot and head injuries. He's never had a lead job before, and he lands on a team with perhaps the worst QB situation in the NFL. But the impulse to value Ivory highly isn't a poor one. This isn't merely a case of a ham-and-egg type player landing a starting job, a la BenJarvus Green-Ellis last year with the Bengals. Ivory really does have skills. In his 256 career carries, Ivory has broken runs of 10-plus yards on 33 of them. That ratio of 12.9 percent puts Ivory 12th among all active RBs with at least 200 carries:

At 222 pounds, Ivory is the second-heaviest man on this list, behind only Stewart. That power/speed combo makes Ivory enticing. I believe he'll probably get hurt, but for as long as he's healthy, I think he easily beats out Mike Goodson and provides flex value at minimum.

Le'Veon Bell, RB, Pittsburgh Steelers: If there's one player I'm worried I've ranked too low, it's Bell. I'm not a huge fan of his collegiate game tape: He seemed indecisive in the hole and took a long time to get up to speed. But you can't fake 244 pounds, and Bell lands in a tremendous situation for fantasy value. Incumbents Isaac Redman and Jonathan Dwyer have fallen out of favor after each got a chance to take over the No. 1 job last year, and while nothing is ever guaranteed for a rookie with the Steelers, Bell will get a clear shot in training camp to win the job. (He's a good pass catcher for a man his size, too.) Over the past three seasons, Pittsburgh is fifth in the NFL in rushing attempts inside an opponent's 5-yard line, and Bell's body makes him a great candidate for that work. My gut still tells me he's not a star, but if I'm wrong, I freely admit that ranking him No. 23 among RBs could come back to haunt me.

Wes Welker, WR, Denver Broncos: The Broncos offense was in harmony with Peyton Manning slinging it to Demaryius Thomas and Eric Decker last year, but the team couldn't pass up signing Welker for relatively short money (two years, $12 million). Will Welker's between-the-numbers excellence draw more of Manning's attention, the way guys like Dallas Clark and Austin Collie did in the past? Will that lead to fewer targets for Thomas and/or Decker? Here are my projections for '13:

If you add up the lost targets among Thomas, Decker, Stokley, Tamme and Dreessen, you get 109 for Welker; the fact that I gave him 135 means I expect Peyton Manning to throw even more than he did last season, when he posted 583 attempts, the third-highest total of his career. Of course, this is all far from certain. You can make an argument that I'm devaluing Decker too much by rating him 21st among WRs, considering he tied for seventh in WR fantasy points last season. But if his big TD total (13) doesn't recur, Decker is likely headed for a fall. Thomas is the truly special outside talent here, which explains why he's eighth on my WR list, while Welker is 15th.

Danny Amendola, WR, New England Patriots: The position Welker left behind in New England, where he saw those 173 luscious targets, is wide open now, and Amendola is the favorite to claim it. He's a bit bigger and has better deep speed than Welker does, which could actually cause him to be an even bigger part of a fairly untested Pats receiving corps than Welker was. But his problem is health. Amendola has missed 20 of 32 games in the past two seasons with some serious injuries. If you could promise me that he'd play all 16 at something resembling full strength, I'd tell you Amendola probably should sniff the top 10 WRs even in a standard league (and in a PPR league, he'd be well inside the top 10). But you can't tell me that, and that's why Amendola is on this list. His health will be one of the massive storylines of this fantasy season. If you get him on the cheap -- and he's the No. 20 WR on my list -- and he winds up healthy, your team will be in spectacular shape.

Josh Gordon, WR, Cleveland Browns: Gordon already figured to be an interesting conversation starter even before his two-game suspension for a failed drug test. (He tested positive for codeine.) As a rookie supplemental pick who'd played no collegiate football since '10, he seemed like a bad bet for instant value in '12, yet Gordon scored five TDs and produced some big plays in a terrible Cleveland offense. The advent of Rob Chudzinski and Norv Turner to the Browns should mean a more aggressive pass attack, and while Gordon doesn't have elite deep speed, he's got good enough wheels to take advantage of his 6-foot-4 frame and outmuscle defenders for the long ball. But remember, Brandon Weeden is under center, and he was nobody's idea of an NFL-ready player last season. Now that Gordon will miss two games, the hype train on him has slowed a bit, and I think that's for the best. Unless you believe Weeden is ready to make a major leap, it's hard to project any Browns WR for big week-to-week production. I have Gordon ranked as my No. 44 WR, keeping in mind that if he tests positive one more time, he's probably looking at a year-long ban.

Rob Gronkowski, TE, Patriots: As the Pats have released Aaron Hernandez because of his legal troubles, Gronk is more important to the team's future than ever. But will he be ready to play Week 1? Multiple surgeries to his broken arm have finally apparently fixed that problem, but Gronkowski also underwent back surgery in June and will race the clock to be ready before Week 1. (He seems like a lock not to be ready for the beginning of training camp.) My opinion is that Gronkowski will play in the opener, Sept. 8 in Buffalo, but that's not certain. To err on the side of caution, I dropped Gronk to my No. 2 fantasy TE slot, behind Jimmy Graham, though I don't put much distance between them. The truth is, of course, that even if Gronkowski misses a game or two, he's still easily among the most valuable players in fantasy, as illustrated by his 38 TDs in 43 career games. But if you draft him and he starts the year on the PUP list (making him ineligible for the season's first six games), well, that would be bad. With Hernandez gone, players like Jake Ballard and (to a lesser extent) Michael Hoomanawanui could become factors. But they are certainly not the kind of fantasy options Gronk is.