What does it take to be a sleeper?

The basic definition is a team that no one is talking about. However, in the NFL—since everyone is talking about almost every team to some degree—it takes more than just a lack of buzz. To truly be a sleeper, people must have a general feeling against a team's potential success. It takes plenty of false narratives and a general uninformed consensus.

The term is intrinsically subjective. It's also contrary to popular opinion. If one sees a bunch of different people labeling a certain team a "sleeper," it's an awfully good bet the team ceased to actually be a sleeper some time ago.

So heading into 2013, which teams have a shot to go against the grain and truly overachieve?

Minnesota Vikings

Last season, I went out on a limb and proclaimed the Vikings a better team than people thought. They rewarded my "faith" in their abilities with a playoff appearance and an MVP season from running back Adrian Peterson.

In Las Vegas-speak, I'm going to let it ride.

Where is the evidence that this team has gotten any worse from last season to this year? Don't think they can get to the playoffs without wide receiver Percy Harvin? Why not? They did so last season.

In addition, their offense should be better and more balanced with receiver additions in Greg Jennings and Cordarrelle Patterson.

Taking Harvin out of the equation should be a boon for quarterback Christian Ponder as well.

At times, the desire to get Harvin the ball led to a departure from the Vikings' bread-and-butter plays. Fundamentally, this should be a run-heavy team with play action and plenty of moving pockets in the passing game. That fits what Ponder does well more than the screen-heavy or gadget sets that worked so well with Harvin.

At times, Ponder was terrible last season, but people forget he had bright spots as well. Weeks 14-16 of 2012 were noted steps forward from the depths of ineptitude into mediocrity, but Week 17 against Green Bay was a fantastic game that catapulted the Vikings into the playoffs.

They could not have gotten into the postseason without that tremendous effort out of Ponder.

In Year 3—after Ponder's second full offseason—they should have the ability to take another step forward with him under center.

It should be noted that popular opinion leans the other way. Rivers McCown said in the Football Outsiders 2013 Almanac:

But Minnesota’s passing-game problems were not just about the passengers, they were about the driver. It doesn’t take a lot of digging to figure out Ponder’s main issue as a quarterback: an inability to consistently connect on deep passes.

Their defense, too, should be able to feature a heavier rotation along the front with first-round draft pick Sharrif Floyd stepping in as a backup 3-technique tackle. Defensive ends Everson Griffen and Lawrence Jackson will put on even more pressure rotating in on the perimeter.

This is all on top of a starting defensive unit that is returning (mostly) intact after finishing right in the middle of the pack last season. There's little reason they shouldn't be in the top 15, if not the top 10, this season on defense.

The bottom line, of course, is running back Adrian Peterson.

Even if he doesn't duplicate last season's efforts, he should be a top back again in the NFL. With the tremendous help in front of him on the Vikings offensive line, he will have plenty of holes to burst through. With another top season from him, it should take the bite out of opposing defenses and keep the Vikings in the running to win far more games than their critics expect.

San Diego Chargers

The Chargers were a better team than former head coach Norv Turner was able to showcase last season. Finishing at 7-9, the Chargers had a top-10 defense.

It was their offense that left them hanging at the end of many games.

Remember, this was a team built around a supposedly explosive offense and a head coach who was said to be a fantastic offensive mastermind. Quarterback Philip Rivers and his offensive compatriots were hamstrung by horrid offensive line play.

Let Andy Benoit explain, via the Football Outsiders Almanac:

The Chargers were ill-prepared last season for turmoil along the left side of their offensive line. Guard Kris Dielman and tackle Marcus McNeill both retired prematurely due to health issues. Their replacements, Tyrone Green and Jared Gaither, had up-and-down seasons plagued by injuries.

Moreover, the issues were exacerbated by Turner's hardheadedness. He continued to lean heavily on a pass-heavy vertical scheme that put undue pressure on Rivers because he had neither the production nor the weapons to make it work.

This year, under new head coach Mike McCoy, there should be much more balance on the offense. McCoy, who helped build offenses for quarterbacks Kyle Orton, Tim Tebow and Peyton Manning, will understand the need to tailor his weekly game plans for the personnel he has.

New offensive tackles D.J. Fluker, King Dunlap and Max Starks are going to give Rivers better protection than last year, as well as a recommitment to the run game. This should lead to fewer sacks, fewer turnovers and potentially more scoring.

Combine all that with a defense that should be as good (if not better) than last season, and the wins should increase from last season—especially in the AFC.

It's a conference where the wild-card spots could easily go to "average" teams. While the Chargers aren't getting anywhere in the AFC West division this season, they could easily end up in the wild-card hunt late into December.

Kansas City Chiefs

Staying in the AFC West with the last sleeper on this list, and I can hear some of you now: "There's no way the Chargers and the Chiefs are both making the playoffs this season!"

Well, I'm not saying that, so let me deconstruct my hastily made straw man.

Maybe they don't both make the playoffs, but I'll bet that both are better than critics expect in 2013, and I'd bet at least one of them are in the postseason.

Why the Chiefs? Why the top of this list? What makes me tell every single radio host from Connecticut to Hawaii that the Chiefs are my "sleeper" team this season?

It isn't just quarterback Alex Smith. It isn't even just head coach Andy Reid.

Don't get me wrong, both Smith and Reid are going to have big impacts in 2013. Smith, especially, is a long-overdue boon for this team that hasn't had solid quarterback play since vintage Trent Green.

The point is not that Smith has to be a Pro Bowler (though he has that potential) and it isn't that he needs to completely turn his career around (though he may have started that very thing under Jim Harbaugh in San Francisco).

No, as long as Smith is mediocre—just average—he can lead this team to the playoffs.

Former head coach Romeo Crennel was never known as a hands-on individual in his previous stops. "Aloof" doesn't even begin to describe the man who is a perfectly nice individual and defensive mastermind, but isn't as engaged as NFL life asks a head coach to be.

Furthermore, and I don't mean to trivialize the incident, but the tragedy that the Chiefs underwent with Jovan Belcher put even more pressure on Crennel and strained team chemistry all the more. Certainly, the incident is much more than a "football matter," but it's impossible to separate the man from a situation that changed his life and made it near-impossible to do his job in 2012.

Now, Reid gets a fresh start.

It's intriguing to me that Reid went from burned out in Philadelphia to now being a breath of fresh air in Kansas City. It speaks not only to the fickle nature of the NFL fanbase, but even more to the low bar that is set for Reid in his new home. Like Smith, Reid doesn't need to be the best. He just needs to be better than what Kansas City had before.

Remember, this team sent six players to the Pro Bowl after last season. These were not "name-only" Pro Bowlers. No, these were legitimate players who deserved to be there: running back Jamaal Charles, linebackers Tamba Hali, Derrick Johnson and Justin Houston, safety Eric Berry and punter Dustin Colquitt.

Each of those players is returning in 2013.

This was already a good team. It just had a couple of giant albatrosses hanging around its collective neck. For that reason—because this is already a good team, no longer saddled with terrible quarterback play and subpar coaching—the Chiefs are a sleeper heading into 2013.

Michael Schottey is the NFL National Lead Writer for Bleacher Report and a member of the Pro Football Writers of America. Find more of his stuff at The Go Route.