Pittsburgh finished 2011 as the NFL’s top defense. Solid, right? They allowed the fewest points per game (14.1), surrendered the fewest first downs per game (16) and gave up the fewest yards per play (4.5). Yet in most leagues, they finished outside the top 10. How’d that happen? Simply put, the Steelers struggled to make big plays. They had the third fewest interceptions (11), the second fewest defensive touchdowns (2) and the second fewest forced fumbles (6). Last I checked, it’s tough to recover a fumble if you don’t force a fumble.

With the delineation between “solid” and “big-play” defined, let’s look at six potential big-play defenses heading into 2012.

1. Green Bay Packers: The Packers have 85 interceptions over the past three seasons. Eighty five. And their 31 picks from 2011 were eight more than any other team. To further illustrate the differentiation between solid versus big play defenses, Green Bay finished last season ranked 19th in defense, primarily because they got up fast on teams and the opposition had to ignore the running game just to remain competitive. No other team surrendered more passing yards than the Packers for that reason, and with all of those pass attempts come the opportunity to make plays defensively.

Whatever the reasoning behind why they’re so good, Green Bay will continue to be a big-play juggernaut for fantasy owners. The fact that they spent four of their first five draft picks on defensive players—including defensive end Nick Perry in the first round—is evidence that focus will remain on causing havoc for opposing offenses. Green Bay’s DST should be one of the first defensive units picked on draft day.

2. Baltimore Ravens: It’s amazing how Baltimore’s defense has been a relevant fantasy option for well over a decade. Each year, the Ravens provide fantasy owners with stellar play that is worthy of a weekly start in spite of their opponent. Unlike every other team listed here, the Ravens are arguably both a solid and a big-play defense. They can both stifle an offense with smothering play-making, and force it into blundering mishaps that light up the fantasy scoreboard. Terrell Suggs’ injury, though, will be felt. He forced seven of Baltimore’s league-leading 21 fumbles last season. Rookie Courtney Upshaw may be thrust into duty in Suggs’ place; Ray Lewis won’t allow him to play like a rookie. Expect him to be productive.

Ed Reed is toying with the idea of either holding out for more money or retiring altogether. He’s one of the top play-making safeties the league has seen in the last quarter century. Conventional wisdom says Reed will show up and play. If that proves true, expect another top-10 finish for one of fantasy football’s most reliable defenses.

3. Buffalo Bills: In spite of having the second most defensive touchdowns (7) last season, the Bills were essentially a hit-or-miss defensive unit in 2011. They gave up a ton of yards and even more points (27.1 per game). The front office noticed the holes on defense and went out to try to fill them—namely by signing defensive end Mario Williams. He will team with second-year pro Marcell Dareus at defensive tackle along with linebackers Nick Barnett and Kirk Morrison to form perhaps the biggest sleeper unit entering the 2012 fantasy season. Shawne Merriman is not what he once was, but he can still be a force if used sparingly.

The Bills finished last season tied for the fewest sacks in the league (29), but be assured, that will change this year. And sure, we don’t know how teams will fare, but Buffalo’s fantasy playoff opponents certainly look enticing: St. Louis in Week 14 and Seattle Week 15—both at home—followed by a Week 16 showdown in Miami. The big names on Buffalo’s defense could increase this unit’s draft stock by a round or two, but if you make the choice to select this defense at the right time of your draft, it could pay off for you in a big way.

4. Detroit Lions: Next to the Giants, many look at Detroit’s front four as the next best thing. Kyle Vanden Bosch, Cliff Avril, a (supposedly) motivated Nick Fairley, and Ndamukong Suh are as tough as nails, and even though Detroit’s defensive unit had some struggles stopping teams in 2011, they were tied for the second most defensive touchdowns (7) and the sixth most sacks (41). They also forced 17 fumbles—fourth best in the league.

Keep in mind, they did all of that with a secondary that was less than stellar, as that playoff debacle against New Orleans showed. They fortified that unit during the offseason via the draft and free agency, so it should be better. Perhaps the most unnoticed part of the defensive unit is the continuity it enjoys by having defensive coordinator Gunther Cunningham calling the shots for a fourth consecutive season. The Lions will undoubtedly be in a number of high-scoring games, so the defense should have plenty of chances to force mistakes and rack up fantasy points at a nice clip.

5. New York Giants: The Giants were banged up last year at both the linebacker and secondary positions. Still, they finished with the third most sacks in the league. New York is on the list primarily because of the rotation they have on the defensive line. Jason Pierre-Paul, Osi Umenyiora, Justin Tuck and Mathias Kiwanuka make up part of what many consider the best pass-rushing front four in the league. They pressure the quarterback relentlessly, and that directly results in sacks, quarterback pressure and, ultimately, errant throws that are primed to be intercepted.

What's more, they seem to always show up when they're needed most. The Giants closed out last season with 11 sacks in the last two games—games they needed just to make the playoffs. Also, Antrel Rolle and Kenny Phillips headline a productive secondary that complements very well the defensive line’s onslaught of the opposing passer. New York isn’t going to shut many teams down defensively, but they’re a big play waiting to happen. Make sure they’re in your lineup when that occurs.

6. Cincinnati Bengals: Cincinnati led the league in three-and-outs last season and was one of the best units at sacking the quarterback. They finished with the third most sacks in the league (45) even with none of them getting double-digit sacks. Defensive end Michael Johnson is coming into his own and will look to be a more consistent threat off the edge. Cincinnati attempted to strengthen its secondary by selecting Dre Kirkpatrick in this year’s draft. He will add to a solid backend that includes the return of Leon Hall, veteran Nate Clements and free agent signee Terence Newman.

A more subtle reason to eye Cincy’s defense is their relatively easy schedule to begin the season. During the first six weeks, they play the habitually offensively-challenged Cleveland Browns twice, Jacksonville and its “stellar” quarterback situation, and Miami at home. The Bengals defense should be able to make headway during this stretch while becoming a big-play defense that pounces on lesser offenses.