In signing Von Miller to a six-year, $114.5 million contract extension Friday, the Denver Broncos ensured that they'll again have one of the NFL's most prolific pass rushes in 2016.

Since he entered the league in 2011, Miller has piled up 60 sacks, second to only J.J. Watt during that span. And he was the main reason why the Broncos got to opposing quarterbacks at a higher rate than any team in the league in 2015.

During the offseason, teams like the New York Giants and Arizona Cardinals made significant moves to bolster their respective pass rushes. This is an area where coaches across the league feel like they never have enough and always want more.

Keeping that in mind, below is a rundown of the five best and five worst defenses in terms of producing sacks in 2015. Which of these units might drop off in 2016, and which are poised to improve? Here's a look.

Top 5 - Sack Percentage (2015) Team Sack Percentage Denver Broncos 8.10% New England Patriots 7.30% Houston Texans 7.30% Detroit Lions 7.30% Pittsburgh Steelers 7.00%

Top five

Denver Broncos -- They brought opposing quarterbacks down on 8.1 percent of their dropbacks. While sack numbers can sometimes be misleading, that wasn't the case here. Denver was first in pressure percentage (takes into account QB hurries and hits) as well. The Broncos lost defensive tackle Malik Jackson in free agency, but with Miller, DeMarcus Ware and defensive coordinator Wade Phillips all back, this group is set up to be an elite pass-rushing unit once again.

New England Patriots -- The pass rush is a serious question mark going into 2016 now that Chandler Jones (12.5 sacks) is in Arizona. The Patriots finished 19th in pressure percentage and are counting on new additions like Chris Long and Shea McClellin to give them a boost. The Patriots haven't fielded a really good defense in awhile. They've finished outside the top 10 in defensive efficiency for nine straight seasons, according to Football Outsiders' DVOA metric. No team blitzed less often than the Patriots last year, but that could change if they have trouble generating a pass rush without Jones.

Houston Texans -- J.J. Watt and Whitney Mercilus combined for 29.5 sacks, more than any other duo in the NFL. The Texans finished seventh in pressure percentage, and the defense performed well even when it wasn't putting heat on opposing quarterbacks. According to Football Outsiders, only the Broncos and Seattle Seahawks were better than the Texans in situations where the defense generated no pressure. Houston focused almost exclusively on offense during the offseason and clearly feels like it can get a repeat performance from the defense.

Detroit Lions -- They were an example of high sack numbers not necessarily equating to quality defensive performance. The Lions were just 20th in pressure percentage and 19th in overall pass defense. Defensive end Ezekiel Ansah had 14.5 sacks last season, but overall this is not a unit that has the pieces to scare opponents in 2016.

Pittsburgh Steelers -- They had to send extra defenders to generate pressure in 2015. The Steelers blitzed on 35.1 percent of opponents' dropbacks, the eighth-highest rate in the league. That led to a big sack total, but the Steelers finished 27th in pressure percentage. The defense is hoping to get more production from 2015 first-round pick Bud Dupree, but this is a unit that will likely have to scheme up ways to generate pressure once again.

Bottom five

Bottom 5 - Sack Percent (2015) Team Sack Percentage Atlanta Falcons 3.20% Buffalo Bills 3.30% New York Giants 3.40% San Francisco 49ers 4.70% New Orleans Saints 5.20%

Atlanta Falcons -- Any way you slice it, they had the worst pass rush in the NFL. The Falcons finished last in sack percentage and last in pressure percentage. They're counting on Vic Beasley to make the second-year leap, but lack of pass rush looks like a major issue for Dan Quinn's defense.

Buffalo Bills -- Their pass rush wasn't much better than Atlanta's. Rex Ryan's group finished 31st in sack percentage and 29th in pressure percentage. The Bills didn't have a single player finish in the top 50 in sacks league-wide. Mario Williams (five sacks) was tied for the team lead, and he's now in Miami. First-round pick Shaq Lawson suffered a shoulder injury in the spring. Ryan will have his work cut out for him trying to produce an effective pass rush with this group.

New York Giants -- Of the teams in the bottom five, the Giants made the biggest splash to help their pass rush by adding Olivier Vernon (25.5 sacks the past three seasons). But the Giants' bigger issue might be what happens on the back end when they actually get to the quarterback. Football Outsiders took a look at how defenses performed on plays where they produced pressure. Only the Jacksonville Jaguars and San Francisco 49ers netted worse results than the Giants in those situations. That speaks to scheme and issues in coverage, where the Giants are hoping cornerback Janoris Jenkins can give them a boost.

San Francisco 49ers -- They were an example of the pass rush being better than the sack numbers indicated. The 49ers ranked 13th in pressure percentage, but, like the Giants, getting to the quarterback didn't lead to defensive success because of issues in the back end. Aaron Lynch was tied for the team lead with 6.5 sacks last season, but he's been suspended for the first four games. The 49ers will be counting on first-round pick DeForest Buckner to have an instant impact.

New Orleans Saints -- They were the worst pass defense and the worst overall defense in the NFL. Cameron Jordan had 10 sacks last season, but he got virtually no help up front. The Saints are hoping first-round pick Sheldon Rankins and free-agent signee Nick Fairley can give them a lift.

* Numbers courtesy of ESPN Stats & Information unless otherwise noted.