The word "sleeper" gets thrown around a lot in the world of fantasy football, to the point where an actual definition may vary from person to person. In general, sleepers are NFL players that may be flying relatively under the radar in a particular field. That could be an under-rostered player in season-long leagues, a player with an exciting matchup in a given week, or even a potential star just ahead of their true breakout.

In any case, we all need to find a sleeper from time to time. Whether you're a fantasy football hipster looking to roster an exciting new player before your league-mates hear about him, a daily fantasy manager looking for a lower-salary player to fill out a lineup loaded with studs, or even just a manager in a pinch due to byes or injuries, we have you covered. We'll be bringing you six fantasy sleepers each and every week throughout the season.

Fantasy Football Week 15 Sleepers

Joe Flacco, QB, Cleveland Browns

FanDuel Salary: $7,100

The Chicago Bears' defense has looked much improved lately, but even after the addition of Montez Sweat at the trade deadline, it still feels like they're outperforming their rostered talent. While they've allowed 13 or fewer points in 3 of their last 4 games, it's worth noting that those games came against the Carolina Panthers, the regression-finally-hit Joshua Dobbs-led Minnesota Vikings, and a pair of games against the Detroit Lions -- one of which saw them giving up 31 points. In other words, it looks like they're due for a bit of a wakeup call.

The Cleveland Browns' fourth quarterback on the season might not typically sound like the kind of person capable of delivering that wakeup call, but Joe Flacco has actually been pretty nice since taking ahold of the reigns in Cleveland. Since that takeover, the Browns are averaging a healthy 25.0 points per game -- something they weren't even doing when their intended starter was healthy. In two starts, Flacco is averaging a serviceable 19.3 FanDuel points per game.

If you're in need of a quarterback after Justin Herbert's season-ending injury, you'll probably be pretty stoked to find 19.3 fantasy points on your waiver wire. Flacco's Week 15 opponents could be softer than you might think at first glance, putting him in position to exceed expectations in fantasy.

Rashod Bateman, WR, Baltimore Ravens

FanDuel Salary: $5,100

We all have players we just can't seem to quit. For me, that's Baltimore Ravens wideout Rashod Bateman. The former first-round pick has flashed moments of promising potential but, between injuries and inconsistencies, just hasn't been able to put it all together. He's been close a few times this season but is ultimately averaging just 3.8 anemic fantasy points per game.

He's not playing all of Baltimore's snaps, but he is running a route on a good chunk of Lamar Jackson's drop backs and could be in for efficient production in Week 15 as the Ravens take on the Jacksonville Jaguars. The Jags' defense is in an active state of collapse at the moment, surrendering over 30 points to backup quarterbacks in back-to-back weeks while giving up an absurd 880 yards of offense.

Three of their starting defensive backs are seriously banged up and in danger of missing Week 15, meaning the Ravens' passing attack could be queued up for its biggest day of the season. If there was ever a spot for Bateman to hit, this would be it.

Jonathan Mingo, WR, Carolina Panthers

FanDuel Salary: $5,400

It's no secret that the Carolina Panthers are having a miserable time this season. Their offense has scored the third-fewest points and has only topped 200 passing yards once -- when Andy Dalton made his lone start of the season. It's been bleak.

But just because things have been bad doesn't mean we need to steer completely clear of the Panthers' players in fantasy. If you're looking for a potential sleeper wideout this week, Jonathan Mingo might be worth consideration. The rookie second rounder is seeing too much volume to fully ignore. In the two games since the Panthers let go of head coach and frequent play-caller Frank Reich, Mingo has drawn 19 targets, which ties him for the ninth-most across the league in that stretch of time. It has only resulted in 8 catches for 91 scoreless yards, but that kind of volume could be a sign of better weeks to come.

This week he'll take a crack at the Atlanta Falcons' defense, which has performed fine during the year while playing a cakewalk schedule. They're far from a matchup to full-on avoid. He's a downfield receiver with an 11.1 average depth of target (aDOT) facing a team with the sixth-highest defensive aDOT allowed (8.6 yards).

If he can convert just a couple of his deeper looks from Bryce Young, he'll be in good shape for a solid fantasy outing.

Ty Chandler, RB, Minnesota Vikings

FanDuel Salary: $6,000

The Minnesota Vikings are going to look a little different than usual when they take on the Cincinnati Bengals on Saturday. Not only will they be starting their fourth different quarterback of the year (Nick Mullens), they'll also likely be giving running back Ty Chandler his first career start. The team ruled out starter Alexander Mattison with an ankle injury, putting Chandler in the spotlight in Week 15.

Chandler isn't a tackle-breaking bruiser like Mattison, but he's still averaging a healthy 4.1 yards per carry on the season. We'll want to see him maintain that efficiency with his expanded role, but it's a good starting point for a back we haven't seen much else from. He's been involved in the Vikings' passing game, as well, giving him something resembling a floor for fantasy in his debut start.

The Bengals' rushing defense has been shockingly good over the last two weeks while allowing just 117 combined rushing yards against the Jags and the Indianapolis Colts, but they were giving up an average of 139.6 rushing yards per game up until those two games.

It seems like Chandler will have his work cut out for him against the Bengals' front, but there are worse matchups out there.

Chase Brown, RB, Cincinnati Bengals

FanDuel Salary: $5,200

On the flip side of the same game, we have Cincinnati Bengals running back Chase Brown, whose explosive athleticism has provided some juice to the Bengals' ground game over the last two weeks. In those games, he has averaged an efficient 5.1 yards per carry behind starter Joe Mixon and caught all 3 of his targets for 80 yards -- even taking one 54 yards all the way to the house. He's looking like the lightning to Mixon's thunder, and the Joe Burrow-less Bengals have no reason to take his opportunities away.

The Vikings' defense has unfortunately been consistently strong against the run this season. They're allowing the fifth-fewest fantasy points per game to the position (15.1), so we may need to temper expectations for the exciting rookie. He should still see solid work -- he's handled 20 touches over the last two weeks -- and shouldn't get phased out of a game featuring two backup quarterbacks going head to head.

He should still be in a good position to help out fantasy teams desperate for running back help in Week 15.

Chigoziem Okonkwo, TE, Tennessee Titans

FanDuel Salary: $5,000

Tennessee Titans tight end Chigoziem Okonkwo has started chaining together solid performances, which is good enough to put him on the map for fantasy football. The second-year playmaker has been establishing himself as a threat in the passing game and has put up 153 receiving yards in his last 3 games.

The Titans' passing game isn't the most consistent, but its lack of pass-catchers means that Okonkwo's role shouldn't be going anywhere. Behind DeAndre Hopkins, there's no one else earning targets or creating yards. Since stepping up three weeks ago, his 17 targets rank 9th-most at the tight end position, putting him firmly in tight end streamer territory.

This week he'll get a prime matchup against a Houston Texans defense allowing 11.4 fantasy points per game to tight ends (fourth-most). The Jets' tight ends just put up 94 receiving yards on this Texans defense, so it feels pretty safe to stream any tight end with a pulse against them at the moment.

Interested in playing NFL DFS? Head over to FanDuel’s daily fantasy football lobby to see all the offerings for this week's slates.

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The above author is a FanDuel employee and is not eligible to compete in public daily fantasy contests or place sports betting wagers on FanDuel. The advice provided by the author does not necessarily represent the views of FanDuel. Taking the author's advice will not guarantee a successful outcome. You should use your own judgment when participating in daily fantasy contests or placing sports wagers.