NFL defenses have typically been volatile year after year, as it’s been difficult for teams to maintain an elite unit. However, some of the league’s top defenses have been mainstays in the top 10 as of late.It’s difficult to climb out of the bottom tier of defenses and become a good one. Last season, the Seattle Seahawks went from good to elite and the Jacksonville Jaguars went from bad to top 10. So, which defenses have made enough off-season changes to break out this season? Let’s take a look.Indianapolis ColtsThe Colts hired a top-notch play caller in Lou Anarumo last season, but unfortunately, they were hit hard by the injury bug. Their best player, DeForest Buckner, had season-ending neck surgery after Week 9, corner Charvarius Ward only played seven games because of multiple concussions, and cornerback Sauce Gardner, for whom they traded two first-round picks, tore an Achilles tendon after four games in a Colts uniform. In Weeks 1-7, with a healthy Buckner and Ward, the Colts ranked fourth in defensive EPA per play. It’s a small sample size, but it gives a glimpse of what Anarumo can do with some talent to utilize.How Indianapolis Colts rebuilt EDGE roomThe Colts have a better defensive roster now than at the beginning of last season with the addition of second-round linebacker CJ Allen, who will help fortify the run defense, and I’m intrigued by how Anarumo will use third-round pick A.J. Haulcy. Haulcy is a safety who is best utilized around the line of scrimmage and could fit into the role of a modern big nickel.Ward and Gardner can be one of the best cornerback duos in the league and allow Anarumo to play man coverage on the outside and blitz when their four-man rush isn’t getting home. The pairing will allow the Colts to be unique defensively with so many teams moving toward more two-high, zone-heavy schemes. Anarumo’s strength is his creativity and willingness to change up what he does from week to week. Health will be an issue to watch, but the Colts defense will present a very different look than offenses will be used to seeing.Carolina PanthersThe Panthers have been intentional in how they’ve constructed their defense through free agency, signing players that fit well into coordinator Ejiro Evero’s system. Last year, they signed cornerback Mike Jackson and safety/nickel Tre’Von Moehrig. Jackson had a career season and though Moehrig was expensive, his versatility was utilized effectively. This offseason, the Panthers signed edge linebacker Jaelan Phillips and linebacker Devin Lloyd. Phillips gives the Panthers a stout run defender on the edge and some much-needed pass rush juice. Second-year edge Nic Scourton also played well down the stretch and could develop into an impact starter.Evero is respected around the league and has been a serious head coach candidate in recent cycles. Carolina’s poor defensive rankings during his tenure have more to do with injuries and a lack of talent. They still have some major weaknesses, but last season, Evero had the most talented group he’s had in Carolina. The Panthers ranked 22nd in defensive DVOA and gave the Rams’ top-ranked offense issues in the regular season and the wild-card round.Evero is from the Vic Fangio tree, but he hasn’t been able to use as many two-deep coverages as he wants because of the Panthers’ weakness against the run. They ranked dead last in defensive rushing success rate in the last two seasons. Phillips will help to disrupt outside runs, while Lloyd’s ability to play all over the front, including the line of scrimmage, will allow Evero to get creative with shifting or stemming his fronts before the snap. That will make it harder on offensive lines to execute their blocking schemes.Last season, the Jaguars, with Lloyd, ranked third in defensive EPA on passes between the numbers, under 15 air yards. The Panthers ranked 26th in the same metric. Lloyd’s pass coverage was a big part of the Jaguars’ ability to cover the middle of the field and the Panthers hope his athleticism will improve their secondary and create turnovers. Evero finally has the pieces he needs to run the system that he wants to. The Panthers have some depth issues, but this should be the year that Evero leads a top-10 defense.Dallas CowboysThe Cowboys defense will grow along with first-year play caller Christian Parker. Parker was a highly regarded young coach, having worked under Fangio since 2021. Fangio is the architect of the current defensive meta, and Parker knows how to install his defense and, most importantly, his curveballs. Parker will certainly put his own spin on the system, but the foundation will come from Fangio and the Cowboys successfully drafted Fangio prototypes for Parker, starting with safety Caleb Downs, who will play the important nickel position in the Cowboys system.For this sort of defensive structure to work, you must have a front capable of defending the run from a light box, and the Cowboys have that with defensive tackles Quinnen Williams and Kenny Clark. New edge linebacker Rashan Gary has been inconsistent as a pass rusher, but he’s a strong run defender. Rookie linebacker Jaishawn Barham, depending on how he develops, can give them a move-piece linebacker who will allow Parker to stem the Cowboys’ front similar to what Zack Baun does for the Eagles. Downs was also a dynamite run defender in college and will consistently be part of the run fit.The Cowboys will depend on youth. They need second-round pick Malachi Lawrence to provide them with instant juice off the edge and second-year corner Shavon Revel Jr. to push Daron Bland, whose gambling play style doesn’t fit in the system, out of the starting lineup. The Cowboys may not push to be a top-10 unit, but they can make a huge improvement from being the 32nd-ranked defense in DVOA, FTN’s efficiency metric that accounts for strength of schedule. With their high-scoring offense, a jump to between 16th and 20th for the defense could make the Cowboys legitimate playoff contenders.Chicago BearsThe Bears had two different defenses last year: Their early-down defense and their third-down defense. They ranked 25th in defensive EPA per snap on first and second down, but ranked seventh on third down. The Bears ranked second on third-and-fourth down with more than seven yards to the first-down marker. The reason was simple: they struggled mightily to stop the run. They ranked 26th in defensive rushing success rate and 27th in explosive rush rate allowed. We saw coordinator Dennis Allen’s ingenuity with his disguises and pressures in obvious passing situations, but the defense didn’t earn enough of those opportunities because it couldn’t stop the run, which resulted in finishing 25th in defensive DVOA.Have the Bears done enough to shore up the run defense? They didn’t upgrade the defensive tackle room much. They added some depth, but Gervon Dexter Sr. and Grady Jarrett remain the starters. The return of corner Kyler Gordon, who played only two games last season, will help the run defense. Free-agent signing Devin Bush will help as well. First-round pick Dillon Thieneman was excellent against the run in college and will add a disruptive force coming from depth against the run as well.Did the Bears do anything to improve their line?Dan WiedererThe weakness at defensive tackle will likely prevent them from being a high-level run defense, but the surrounding pieces could be enough to at least make them average. That would be a force multiplier for them with how good Allen is as a play caller in passing situations. The Bears gave up the sixth-highest explosive run rate in the league last year; if they can cut that figure down, it will have a trickle-down effect for the rest of the defense.Gordon will help their slot coverage tremendously and free-agent signing Coby Bryant is one of the better free safeties in the league who will make their pass defense even better. Although edge Montez Sweat isn’t an ideal No. 1 rusher, he should be aided by a potential Austin Booker breakout season. Booker was affected by injuries but had 4.5 sacks in his last six games, including the playoffs.Tennessee TitansMost of my optimism for the Titans stems from their improved defensive line. The most important part of making a Legion-of-Boom-based system work is having a disruptive defensive line that can get upfield. Jeffery Simmons is one of the most disruptive defensive tackles in the league and the Titans found an excellent running mate for him with free-agent signing John Franklin-Myers (39 pressures and 7.5 sacks last season).The Titans also traded for Jermaine Johnson, who played for Robert Saleh in New York. Johnson hasn’t lived up to his first-round billing but had a promising sophomore season under Saleh in 2023, finishing with 7.5 sacks. They also drafted edge Keldric Faulk in the first round to play opposite Johnson. Both defensive ends have more potential than production, but the defensive tackle duo will be among the best in the league and will be the catalyst for the Titans.Second-year linebacker Cedric Gray was excellent against the run last season and questionable in coverage. Saleh has always needed to have a strong coverage linebacker in the middle of the field to run with big crossers from athletic tight ends and receivers. Linebacker Cody Barton was disappointing in his first season in Tennessee, but he has experience in this system and has been a good coverage linebacker in the past. Perhaps he can bounce back.The Titans rebuilt their secondary through free agency, adding two starting boundary corners in Alontae Taylor and Cor’Dale Flott. They don’t have stars on the back end, but they have enough to hold up and allow their defensive line to eat. The Titans finished 29th in defensive DVOA last season but look ready to make a major jump.