Seeing as how no teams have played a down yet, it makes it difficult to gauge which defenses will be improved in 2012. But based on the decisions they made in free agency and the draft, these five teams should be improved defensively next season.

Buffalo Bills
Think of the impact that Julius Peppers has had with the Bears the past two seasons – that’s exactly what Mario Williams could do for the Bills in 2012. Buffalo’s defense struggled last season mostly because the pass rush was non-existent. So GM Buddy Nix lured Williams to Buffalo this offseason and made sure he didn’t leave the city without first signing a contract. Nix also signed Mark Anderson, an experienced situational pass rusher that should benefit from playing opposite Williams in the Bills’ “new” 4-3. Adding cornerback Stephon Gillmore should also help Buffalo on the backend while Nigel Bradham and Tank Carder will add depth to the linebacker corps. We’ll have to see how the Dave Wannstedt hire pans out but for now, there’s no question the Bills have upgraded their pass rush in one offseason.

Dallas Cowboys
With the moves they made this offseason, the Cowboys’ defense could transform from a top 15 unit into a top 10. DeMarcus Ware, Jay Ratliff, Anthony Spencer and Sean Lee comprise a solid front seven but Dallas struggled on the back end in 2012. So Jerry Jones invested $50.1 million and a second round pick on his cornerback positions this offseason with the additions of free agent Brandon Carr (the best CB on the market) and first-round pick Morris Claiborne (the best CB in the draft). It’s never guaranteed that a big money free agent or a rookie will make an immediate impact but at least on paper, the Cowboys have definitely improved their secondary. The signing of Dan Connor was also somewhat underrated as well. He struggles at times in coverage and he’s not a pass rusher but he’ll be perfect for what Dallas signed him for: an insider ‘backer that can bolster the run defense.

Atlanta Falcons
The Falcons were productive this offseason in re-signing John Abraham (their best and sometimes only pass rusher last season), safety Thomas DeCoud (who is better than his reputation would suggest), and situational pass rusher Kroy Biermann (who appeared to be distracted last year, although marrying a reality TV star and parenting a newborn will do that to a man). But fans grew aggravated by GM Thomas Dimitroff’s inactivity in free agency and expressed disappointment that the team didn’t go after big money talent like Mario Williams. (Fans were also upset that the team didn’t re-sign MLB Curtis Lofton, who wound up landing with division rival New Orleans.) But the day before the draft Atlanta swung a deal that could only be considered as a steal. Acquiring a three-time Pro Bowler in Asante Samuel for a seventh round pick was a bargain for any team, especially one that struggled getting off the field last season on third downs. Furthermore, the hiring of defensive coordinator Mike Nolan was a huge coup for the Falcons, who should be more aggressive and better equipped to handle explosive offenses like New Orleans, Green Bay and New York. No, the Falcons weren’t very active in free agency this year. But the re-signing of Abraham, the acquisition of Samuel and the hiring of Nolan should be more than enough to make this an improved Falcons squad.

Philadelphia Eagles
After struggling early in the season, the Eagles wound up being a top 10 defensive unit in 2011. But here’s why they’ll be improved in 2012. Juan Castillo has a full year of experience under his belt and the pressure he faced last year being a first-time defensive coordinator should lessen. Andy Reid also hit a home run in this year’s draft. Fletcher Cox has top 10 talent and the Eagles landed him at No. 12 (after moving up). Mychal Kendricks is undersized for the position but he was extremely productive at Cal, he hits like a Mac truck and he plays at 110mph every down. Vinny Curry is raw but he has potential as a pass rush and the only reason Georgia cornerback Brandon Boykin fell to the fourth round was because he broke his leg at the Senior Bowl and was limited in pre-draft workouts. Otherwise, he’s a second-round prospect. Re-signing Derek Landri was also good for depth purposes and acquiring DeMeco Ryans from Houston should help the run defense.

St. Louis Rams
The Rams are a bit of a wildcard but considering they ranked 22nd in yards allowed, 31st in run defense and 26th in points allowed, there’s really nowhere to go but up. There are five moves the Rams made this offseason that should prove to beneficial in 2012. The first was hiring defensive-minded Jeff Fisher as head coach, who brought assistants like Mike Waufle and Chuck Cecil with him to St. Louis. The Rams also added scrappy cornerback Cortland Finnegan and defensive tackle Kendall Langford, who is a freaking house. Drafting run-stuffing DT Michael Brockers to play alongside Langford was also big and former Florida cornerback Janoris Jenkins could prove to be worth the gamble that new GM Les Snead took in the second round. Keep an eye on William Hayes, too. He was limited last year because of a shoulder injury he suffered in Week 1 but he’s someone that could potentially see his playing time increase because he’s he can play the run and provide some pressure. The Rams screwed the pooch by not taking an outside linebacker in the second round, but all in all they had a productive offseason and should be improved next year.

Woody Paige of the Denver Post isn’t too big on Josh McDaniels’ choice of Mike Nolan to fill the Broncos’ vacant defensive coordinator position.

It must be downright discouraging and demoralizing for somebody who has served as a defensive coordinator, then head coach, for 14 1/2 seasons — with five different teams — yet reached the playoffs only TWO of those years, won more than 10 games just once, had a losing record in eight seasons (and only four or five victories four times), was fired several times and, in the biggest game all his teams played, saw the defense reduced to ashes (44 points).

Say hello again to Mike Nolan, your new defensive coordinator.

He is Josh McDaniels’ first hire.

The Broncos’ most critical need was an extraordinary defensive coordinator, and they get an offensive coordinator, who brings in, for the Broncos, another ordinary defensive coordinator. The Broncos selected a baby-faced coach, and he selects a second-hand coach.
It’s inexplicable.

Nolan was named the 49ers’ head coach in 2005. He won fewer than half his games, and did not make the playoffs, before being fired after seven games (2-5) this season. In San Francisco Nolan’s defenses ranked, in points allowed, Nos. 30, 32, 20 and 23. They permitted 30 points or more 18 times.

The future of McDaniels and Nolan will depend on the 3-4, tried and trashed by the Broncos temporarily last season, but they have to depend more on exceptional unrestricted free agents and a No. 1 pick on defense who can step in immediately. The Broncos, despite a plethora of linebackers, could use one more who can stop the run (Channing Crowder), and they must find a starting safety (oft-injured Mike Brown) or two, another corner (Nnamdi Asomugha) and two defensive linemen (Julius Peppers, Bertrand Berry).

And Mike Nolan has to prove why Broncophiles should not be down- wrong discouraged and demoralized.

It’s hard to argue with Paige because Nolan did absolutely nothing to restore the 49ers’ defense, even though they added key pieces in Patrick Willis, Nate Clements, Michael Lewis and Justin Smith during his tenure there. It’s also a bit premature at this point to trash any coaching hire (after all, look at the ’08 new coaching class of Tony Sparano, Mike Smith and John Harbaugh), but I fail to see how McDaniels/Nolan is better than Mike Shanahan at this point.

Let the retooling begin…

The Green Bay Packers have fired defensive coordinator Bob Sanders and five assistant coaches, four on defense.

In addition to Sanders, defensive tackles coach Robert Nunn, defensive ends coach Carl Hairston, secondary coach Kurt Schottenheimer, cornerbacks coach Lionel Washington.

The only defensive coaches who were retained was assistant head coach / linebackers Winston Moss and quality control assistant Joe Whitt Jr.

McCarthy also fired strength and conditioning coach Rock Gullickson.

The move suggests that coach Mike McCarthy will hire a defensive coordinator who will have a say in which assistants he brings with him. The leading candidate would be former San Francisco 49ers coach Mike Nolan, who hired McCarthy as his offensive coordinator in 2005 and is close to the current Packers coach.

The defense really struggled this season. The Packers were 20th in total yards allowed, 22nd in points allowed and 26th against the run. Last season, they were 11th, 6th and 14th in those categories, respectively. Consistent pass rush was always a problem and the Packers just could not stop the run when they needed to. They were second (to Houston) in points allowed in the fourth quarter, which explains why they went 0-7 in games decided by four points or less.

He looked like a genius in 2007, but if not for that, there would be a strong possibility that McCarthy should be shown the door as well. One more season like this and he’ll be gone too.

I like the idea of bringing Mike Nolan in to run the defense. The 49ers weren’t terribly good when he was there, but the defense was solid and my guess is that Nolan is hungry to rehab his reputation as a top defensive mind.

Ray Ratto of the San Francisco Chronicle writes that firing head coach Mike Nolan was the right move by the 49ers, but the timing was awful.

This is the theme that runs through the 49ers’ administration – it has a spectacularly lousy sense of timing.

Look, Nolan has been a toe in search of a tag since the end of last season. His flaws have been examined in minute detail, and his gifts do not measure favorably by comparison. This day was coming. It simply makes no sense to having it come Monday, unless you recognize that the 49ers don’t do anything through planning. It’s knee meets jerk, time and again.

Nolan got fired for a lot of reasons. He got fired when he did because the failings of the franchises were leading back to John York, and York hired Nolan and gave him all the decision-making power and the pulpit to be the face of the franchise so that he would provide a cushion between York and the public.

So York decided, reflexively and with no discernible strategy save getting out of the line of fire, that Nolan had finished serving the purpose for which he had been hired. York couldn’t wait one more week, when a firing would have made sense. He had to do it now, because … well, just because.

Ratto’s probably right, but once the cat was out of the bag, it’s kind of hard to get the thing back in. Sometimes it’s better to just cut your losses (at whatever time you do it) and move on. Singletary is not in a great place now, but he’s always been a motivator and who knows, maybe the 49ers can come together in the wake of this move and compete. They certainly have enough talent; they just need direction.