Defenses in fantasy football are a fickle beast to figure out. Touchdowns can sway the course of a defense's fantasy season, but are nearly impossible to predict. This is why many fantasy players are fans of a strategy called "streaming defenses." If you've been playing for years, this is nothing new to you, but for those unaware, what this entails is using a waiver claim most weeks to acquire a defense with an enticing matchup. This doesn't always work, but for many players it's a better option than rolling the dice with an average defense week after week.
So with this in mind, here are some lesser-owned defenses to target for Week 15.
Baltimore Ravens D/ST (40.3 percent owned) vs. Jacksonville Jaguars
Any way you cut it, the Jacksonville offense is a favorable matchup for opposing defenses. The Ravens defense has suffered some big personnel losses lately (Jimmy Smith, Haloti Ngata) but still has the talent to make life miserable for Blake Bortles and co. on Sunday.
The Ravens defense has scored double-digit fantasy points three times in their last four games, and just sacked Ryan Tannehill six times last week. Only two quarterbacks have been sacked more frequently than Bortles so far this season meaning the Ravens' pass-rushing duo of Terrell Suggs and Elvis Dumervil should be able to get home early and often. If the Ravens are still available in your league they're worth grabbing as one of the best streaming options of the week.
New York Giants D/ST (4 percent owned) vs. Washington Redskins
The Giants defense had been an afterthought for much of the season, but they've caught fire in recent weeks. In fact, they've scored 46 percent of their fantasy points on the season over the last two games. That's why they're an interesting streaming option this week against a Redskins offense that has the distinct look of a raging dumpster fire.
Over the last four weeks, the Washington offense has allowed the second-most fantasy points to opposing defenses, thanks in large part to their offensive linemen stopping defenders about as successfully as saloon doors. Meanwhile, the Giants have notched 15 sacks over the last two weeks, which should have Jason Pierre-Paul and friends licking their chops for this mathcup.
Green Bay Packers D/ST (48.4 percent owned) at Buffalo Bills
The Packers defense didn't perform well in Week 14, but this unit has been gaining steam in weeks prior. They undoubtedly perform better at home than on the road, but when their upcoming road matchup has Kyle Orton as the quarterback, they can still be a viable streaming option.
Orton was flustered last weekend by the Broncos pass rush and threw two interceptions as a result. The Packers pass rush has been steadily improving with Clay Matthews playing more middle linebacker in recent weeks, and Green Bay's opportunitic secondary is only getting better with the emergence of rookie safety Ha Ha Clinton-Dix. The Bills aren't the most ideal matchup, but in a tough week for streaming defenses fantasy owners should be able to rely on the Packers to put up solid numbers in Week 15.
Cleveland Browns D/ST (25.3 percent owned) vs. Cincinnati Bengals
Under head coach Mike Pettine the Browns defense has found ways to stuff the stat sheets, but its lofty 23 fantasy points last week were aided by two defensive touchdowns. Andy Dalton has been up and down recently, scoring seven touchdowns over his last three games, but also turning the ball over five times during that same span. Playing Dalton on the road in a must-win game for Cleveland could favor the Browns defense as they know the onus is on them to push this team into the postseason. They aren't one of my favorite streaming options this weekend, but with so few good matchups to play they're worth a shot.
Good matchups: STL vs. ARI (Thurs.), SEA vs. SF, DET vs. MIN
Matchups to avoid: PHI vs. DAL, CHI vs. NO, ATL vs. PIT
Frisky and risky streaming plays:
-- Alex Gelhar is a fantasy and features writer for NFL.com. Follow him on Twitter @AlexGelhar.