The definition of the term "sleeper" is in the eye of the beholder. If you had asked your buddy who his favorite sleeper was for 2009, he might have said "Chris Johnson" or he might have said "the Giants' Steve Smith," or he might have said "Justin Forsett." All of those answers would have been correct; they were just correct in different ways.
So let's look for the best sleepers and scariest potential busts for 2010 through four different lenses, in four different categories:
In this category, the sleepers have enough upside to establish themselves as unexpected No. 1 options at their position; the busts are possible No. 1 options who might not perform that way.
QB Sleeper: Joe Flacco, Ravens. I'm biting on Flacco as a top-10 quarterback. That means I'm not putting much weight on how poorly he played in the second half last year, because I'm convinced he was pretty banged up. There are questions at tackle (with Jared Gaither in limbo), but Flacco has a giant arm and a couple of good new receivers to throw to.
QB Bust: Kevin Kolb, Eagles. Yes, I like his potential. But too much will be expected of someone with so little experience. The kid dominated the Chiefs and suddenly we're ready to anoint him? Philly will throw it short a lot more, which in itself doesn't spell fantasy glory, and Michael Vick will play significant snaps in the "Spread Eagle."
RB Sleeper No. 1: Jamaal Charles, Chiefs. I'm buying, hook, line and sinker. I know Thomas Jones is on hand. I know Charles has done it for only half a season, that he runs behind a middling offensive line and that he's a slight player who represents an injury risk. But re-watching some of his games from the end of last year, I don't see a huge difference between Charles and Chris Johnson. I have him as a second-rounder, while most everyone else sees him going in the third.
RB Sleeper No. 2: Beanie Wells, Cardinals. So far in OTAs, Wells hasn't even been the starter (Tim Hightower has), but Beanie conquered injury concerns in '09 and looked terrific pounding the rock by season's end. There's a significant chance Arizona decides to get balanced on offense, and Hightower just isn't a dynamic runner. Wells is.
RB Bust No. 1: Frank Gore, 49ers. A few long TDs made his '09 look great, but it wasn't. He had a 10-game stretch last season in which he carried the rock more than 20 times just once. More worrisome is the fact Gore hasn't made it through a complete season without missing games because of injury since his monster 2006 season. I do have Gore as my No. 6 running back, but I feel a little nauseous about it; by no means do I think he belongs in the top four. You'd be forgiven for taking a quarterback or receiver instead of Gore in the first round.
RB Bust No. 2: Ryan Mathews, Chargers. It's kind of unfair to label a kid who has never played an NFL down as a potential bust, but folks are really high on this guy, aren't they? I mean, at Mock Draft Central, he's going, on average, 16th overall. (That's right, not 16th among rushers, 16th overall.) I acknowledge that he has talent and opportunity. But do we really already see him being this bulletproof? I can't buy it. I don't hate him, but I don't think he's a phenomenal talent, either. Maybe he instantly becomes "Young LaDainian." But I smell more risk than people are giving him credit for.
WR Sleeper: Greg Jennings, Packers. Donald Driver is coming off two knee surgeries and is now the same age (35) that Marvin Harrison was when he fell off a proverbial cliff. Plus, I think the Packers figured out how to use Jennings better in the second half last year. Remember, he was the consensus No. 6 receiver in fantasy heading into '09. I have him back in my top 10 for this year.
WR Bust: DeSean Jackson, Eagles. Jackson finished 41st in red zone targets last year. He must keep producing long touchdowns to justify where he'll be selected in fantasy drafts, and with Donovan McNabb gone and Kevin Kolb starting, I question how often that will happen. I have him outside my top 10 among wideouts despite the fact he finished fourth in receiver fantasy points last year.
In this category, the sleepers will be drafted as fringe fantasy starters but could provide much more; the busts will be drafted to be definite fantasy starters but might fail.
QB Sleeper: Chad Henne, Dolphins. Henne has a big arm, and suddenly Brandon Marshall is his playmaker. It's not unreasonable to imagine a top-10 fantasy season for him, and you certainly won't have to pay that price to get him. In a 10-team league, he's a backup quarterback to target.
QB Bust: Matthew Stafford, Lions. Hey, the Lions figure to be a passing offense, which means Stafford will get all kinds of chances. In fact, he'll probably have some good games. But I don't trust that offensive line, and his accuracy was a major problem last year. He doesn't fit the profile of a guy you want as your fantasy backup this year.
RB Sleeper No. 1: Felix Jones, Cowboys. Quick: Who weighs more, Jones or Marion Barber? If the Dallas papers are to be believed, it's Jones. He has bulked up, while Barber has slimmed down. Is there a question of whether Jones can stay healthy as a No. 1 back? There is. But I'm a believer that he'll be afforded that chance, and his 5.9 yards-per-carry average last season makes him look awfully tempting.
RB Sleeper No. 2: Reggie Bush, Saints. Bush is by no means a favorite of mine; he's injury prone and will never be anything close to a No. 1 back. But he's being drafted in the ninth round, on average, and I have him with seventh-round value, so I have to call it like I see it: He's a sleeper. The Saints don't want to use Pierre Thomas as a pure lead back, and Bush gets a lot of red zone work. You also never know when a 70-catch season might be lurking for Bush.
RB Bust No. 1: Marion Barber, Cowboys. See: Jones, Felix. Has Barber lost explosiveness, or was he simply battling leg injuries last year? Some will say that the last time the Cowboys stuck to the plan of using Barber as a "closer" near the goal line without making him a lead back, he scored 16 total touchdowns. But that was in '06. There isn't great precedent for returns to glory of that ilk.
RB Bust No. 2: Jerome Harrison, Browns. If the Browns loved Harrison, they wouldn't have drafted Montario Hardesty in the second round this April, and they certainly wouldn't be raving over Hardesty so much this summer. Harrison is among the quickest backs in the league and should be squarely in the mix to lead Cleveland in carries, but there's no doubt in my mind the Browns want someone else to tote it between the tackles.
WR Sleeper No. 1: Mike Wallace, Steelers. Maybe I'm underrating the impact that Ben Roethlisberger's absence is going to have in Pittsburgh for the season's first month-plus, but I love Wallace this year. He runs a 4.33 40-yard dash at 200 pounds and led the NFL in yards per catch last year. Hines Ward can still play, too, but Bruce Arians likes to air it out, and Wallace should make plays most weeks.
WR Sleeper No. 2: Pierre Garcon, Colts. It's not like he's off the radar screen, but I think fantasy folks are more confused about the Indy passing situation than they should be. Anthony Gonzalez is again a bad bet to remain healthy, and Austin Collie proved he's a better player in the slot. That leaves Garcon single-covered opposite Reggie Wayne on the outside. Sure, he sometimes has shaky hands, but he also has speed. He's still underrated.
WR Bust No. 1: Steve Smith, Giants. There is plenty to love about the consistency and sure-handedness Smith brings to the table, but he doesn't belong in the stratosphere where he's being drafted right now. At least not yet. There are an awful lot of other enticing receiving options on that Giants team, and Smith doesn't make plays downfield or in the red zone. I like him a lot. I just won't own him if I have to draft him in the fourth round of a 10-team draft.
WR Bust No. 2: Dwayne Bowe, Chiefs. He's a knucklehead. Do knuckleheads sometimes get it together all at once? They do. But I don't think it's a wise policy to load up on players you know don't have the mental side of the game down, and then cross your fingers. I acknowledge the possibility that Bowe could be huge in Charlie Weis' offense. But I'm going to let someone else take the chance.
In this category, the sleepers will be drafted to be fantasy backups but have star potential; the busts will be drafted to be fantasy backups but have risk of giving you nothing.
QB Sleeper: Jason Campbell, Raiders. It seems to me that people think Campbell is a worse player than he really is. Does he inspire massive amounts of confidence when the game is late and close? No. But he has a big arm and better accuracy than he gets credit for, and he's a good leader. He's a huge upgrade in a Raiders offense that does have weapons.
QB Bust: Kyle Orton, Broncos. It's very telling that Orton had his best pro season last year, and Denver still brought in two highly drafted kids (Brady Quinn and Tim Tebow) to challenge for his job. He doesn't have a big arm and doesn't take many chances, meaning his high completion percentage usually doesn't mean good fantasy results. And if he struggles this year (in a contract season), he'll likely sit.
RB Sleeper No. 1: Justin Forsett, Seahawks. LenDale White lasted barely a month in Seattle, and nobody really knows what to expect out of Leon Washington, who is returning from a broken leg. As for Julius Jones, well, I think we know exactly what to expect out of him, and it isn't much. I'm not convinced Forsett is a good fit for a one-cut offensive line system, but he's the best rusher the Seahawks have right now (but look for a Marshawn Lynch trade).
RB Sleeper No. 2: Donald Brown, Colts. Brown will be forgotten after his rookie hype, and he'd better figure out how to pass-block better. But this is a contract year for Joseph Addai, and the Colts need to know whether Brown can be the inheritor of their starting job. I'm not expecting miracles, but I am expecting a more equal division of work.
RB Bust No. 1: Willis McGahee, Ravens. Remember LenDale White circa 2008? He had 15 rushing touchdowns and frustrated Chris Johnson owners. And last year? He had two. In '09, McGahee made Ray Rice owners miserable by stealing 12 rushing scores (in addition to two receiving). This is his Baltimore swan song, and I think the Ravens have much more incentive to see Rice in the end zone.
RB Bust No. 2: Laurence Maroney, Patriots. The 2009 season was a fluky touchdown season for Maroney. Seven of his nine scores came from inside an opponent's 2-yard line. Overall, he averaged 3.9 yards per carry and fumbled in several key spots. Don't draft any Patriots running back as though he's going to be a regular fantasy contributor.
WR Sleeper No. 1: Johnny Knox, Bears. The hype has caught up to Devin Aromashodu, and rightly so. I think Aromashodu will be pretty good, even if he is only the Bears' third receiver. But Knox is still flying under the radar in fantasy drafts, and I like him just as much as Aromashodu (and I don't believe enough in Devin Hester). We know Chicago will throw it a bunch, and Knox is a pure burner.
WR Sleeper No. 2: Chaz Schilens, Raiders. As I mentioned above, Jason Campbell's presence makes all the difference. Schilens was set to be Oakland's No. 1 receiver before a broken foot derailed him last summer; now he gets the chance again. Of course, both Louis Murphy and Darrius Heyward-Bey are also big and fast, so Schilens needs to assert himself in camp.
WR Bust No. 1: Robert Meachem, Saints. He's high on a lot of sleeper lists I've seen this year, but Meachem is coming off toe surgery and can't run yet, plus he's on a team with so many great receiving weapons that it's tough to see him as an unadulterated starter. The Saints spread the ball around, which to me means Meachem won't be able to fully deliver on his talent.
WR Bust No. 2: Braylon Edwards, Jets. I'm just not buying. He's as talented as they come, but I always get the sense that Edwards' head is partly somewhere else. There are too many negative factors here: The Jets want to run first, Mark Sanchez has accuracy issues, Santonio Holmes will come back from his suspension in October, and Edwards' hands are always suspect.
In this category, it's deep sleepers only, those players who probably won't be drafted except possibly as handcuffs, but could break out.
RB Sleeper No. 1: Bernard Scott, Bengals. Given his intriguing size/speed combo, Scott could pick up the pieces if Cedric Benson's glass slipper breaks. As of yet, Cincy hasn't signed another viable backup to Benson, so despite the fact Scott looks set to return kickoffs this year, he could also find himself in a plum primary role if Benson gets hurt again.
RB Sleeper No. 2: Arian Foster, Texans. Houston drafted Ben Tate, so Foster quickly faded into Houston's fantasy background. But Tate has battled hamstring issues this summer and nobody knows if Steve Slaton's neck can withstand NFL-style hits, so Foster is reportedly headed to training camp as the No. 1 back. That's very much subject to change, obviously, but you could do worse for a late-rounder.
RB Sleeper No. 3: Jason Snelling, Falcons. There's some question about the correct guy to handcuff to Michael Turner. I'm going with Snelling, who could withstand every-down pounding better than Jerious Norwood (who also is still struggling with a sore hip this summer). Snelling posted a decent 4.3 yards-per-carry average last year.
WR Sleeper No. 1: Laurent Robinson, Rams. Robinson broke his leg in Week 3 last year, but he had taken over the Rams' No. 1 receiving job before that. I know, that's like being the best-tasting Brussels sprout. Still, there are worse things in life than to take a late-round flier on a guy who is 6-foot-2 and runs a 4.38 40.
WR Sleeper No. 2: Jacoby Jones, Texans. Physically, Jones is very much in the mold of Andre Johnson; he's the same size and is nearly as fast. For three years he has been a developmental tease, with mental errors and bad drops, but he also grabbed six receiving scores last year, plus he returned a kickoff for a touchdown. If Kevin Walter falters, Jones could make his bones.
WR Sleeper No. 3: Mike Williams, Buccaneers. Arrelious Benn is the more polished rookie receiver in Tampa, but he has been slowed by an ankle injury this summer, while Williams has shined in camp. Normally it's foolish to pump any rookie receiver, let alone one with a reputation for selfishness and bad behavior, but Williams is big and has deep speed, plus the incumbent Bucs receivers are awful.
Christopher Harris is a fantasy analyst for ESPN.com. He is a six-time Fantasy Sports Writing Association award winner. You can ask him questions at www.facebook.com/writerboy.