The first wave of free agency is passed, with most of the top players already off the market. Even the middle and lower rungs of free agency are largely picked over, and last week we walked you through some of the best bargain signings that teams have made. 

In the space below, we wanted to take a look at some of the more high-profile moves -- signings and trades -- that have the potential to be game-changers because of the ways they change the face of their teams on the defensive side of the ball. Later this week, we'll do the same with the offense. 

Jaelan Phillips and Devin Lloyd, Panthers

The Panthers have long had a desperate need for pass-rush help. They finished the 2025 season with a 29.8% pressure rate, per Tru Media, the second-worst mark in the league ahead of only the decrepit New York Jets. In 2024, their pressure rate was even lower at 25.2%, which was "good" for the single-worst mark in the NFL. They also finished dead last in 2023 and 21st in 2022. It's been since 2021 that they ranked outside the bottom-third of the league, and since 2017 that they actually finished in the top 10. 

Phillips is injury-prone (he played only 12 games combined during the 2023 and 2024 seasons, and he temporarily retired for medical reasons during his college career), but when healthy he is a star pass rusher. He finished last season ranked ninth with 73 pressures, and his 18.8% pressure rate checked in eighth among the 271 players who rushed the passer at least 100 times. He also checked in 20th in pressure rate in 2022, his previous healthy season. 

Only while dealing with major injuries -- a torn Achilles followed by a torn ACL -- did his productivity drop off. Dropping him into Ejiro Evero's unit is going to immediately pay dividends, even if the Panthers had to pay a premium to get him in the door.

Lloyd, meanwhile, is coming off the best season of his career. He was only available in free agency this offseason because the Jaguars declined his fifth-year option due to his up-and-down (at best) play through the first three years of his career. But if he can recapture any of what he did during Year 4, he's going to take the second level of Carolina's defense to a new level as well.

The Panthers still have to add more talent to every part of their defense in order to improve their standing. But adding these two high-level talents is a good start, particularly to improving their pass defense. 

Trey Hendrickson, Ravens

New Ravens head coach Jesse Minter built a high-level defense with the Los Angeles Chargers despite a relative lack of elite talent compared with other top defenses in the league. He's not going to have to do the same thing in Baltimore. He's going to have A+ talent at every level of the defense, including on the edge after the addition of Hendrickson. (There's also Nnamdi Madubuike, if healthy, plus Roquan Smith and Kyle Hamilton.)

Hendrickson played only seven games and collected just four sacks last season, but he was a First Team All-Pro with 17.5 quarterback takedowns in 2024, which was the fourth time in the previous five years that he'd collected double-digit sacks. During that five-year span, Hendrickson collected more sacks than any player except for T.J. Watt and Myles Garrett, and his pressure rate (16.9%) was higher than that of both of those players. In 2024, his pressure rate was sixth-best in the NFL, backing up his sack total.

Hendrickson turns 32 in December so it's possible that the best of his days are behind him. But the upside is high, especially with Minter leading the game plan. The Ravens needed a high-level force coming off the edge for a while after they have been hitting singles and doubles with their pass-rush draft picks, and Hendrickson has a great chance to provide that force in this situation.

Trent McDuffie and Jaylen Watson, Rams

As we detailed last week, the Rams entered the offseason with a significant need at cornerback. They addressed it aggressively by adding a pair of cornerbacks from the Chiefs. They traded first-, fourth- and sixth-round picks in 2026 and a third-round pick in 2027 for McDuffie, whom they then lavished with a record-setting four-year, $124 million contract extension. Then they added Watson and significantly upgraded at the other outside cornerback spot.

Their new defensive backfield should be improved from last season, when the Rams, at times, struggled to contain opposing passing games. That especially stood out in their NFC title game loss to the division rival Seattle Seahawks, but it was an issue at other times as well, like in their regular-season loss to the Panthers and early in their playoff win over Carolina as well.

The following table shows the Rams' secondary this year compared to last, in terms of the men who played the most snaps.

McDuffie is probably at his best playing in the slot. He can move there on occasion because Lake also shifts to safety in certain situations -- he played there on 262 of his snaps last season, according to Pro Football Focus. But McDuffie can also play at a high level on the outside, and Watson has shown that he can be a strong option there as well.

Defensive coordinator Chris Shula should have much-improved personnel to play with this year, and the two massive upgrades at cornerback are a major reason why. The Rams' defense was already pretty good despite the weakness at the position last season, and it should only be better after they addressed it this offseason.

Dre'Mont Jones, Patriots

Jones is a much different kind of pass-rusher than the two the Patriots added last offseason in K'Lavon Chaisson and Harold Landry. Landry is still around, but now he'll be working across from a bigger, pocket-pushing edge as opposed to the smaller, lighter Chaisson. 

Mike Vrabel's defenses in Tennessee favored edges like Jones, who ranked 22nd in the league in pressure rate after his trade from the Titans to the Ravens. Jones has never been a sack master -- his career high is just 7, which he set this past season -- but he's been a productive rotational rushman for a while now and he's coming off the third-most run stops of his career as well, according to Pro Football Focus. 

Minkah Fitzpatrick and T'Vondre Sweat, Jets

The Jets made a ton of signings to upgrade their defense in free agency -- Demario Davis, David Onyemate, Joseph Ossai, Kingsley Enagbare, Nahshon Wright -- but their two most interesting additions came via trade. They acquired Fitzpatrick from the division rival Dolphins for just a seventh-round pick, then gave him a contract extension. And they got Sweat via a trade where they sent Jermaine Johnson to Tennessee to reunite him with former Jets head coach Robert Saleh, who was in New York when Johnson was drafted and when he had his career-best season.

Fitzpatrick should immediately pay dividends as a versatile back-end defender. Fitzpatrick plays all over the field, having lined up for 345 snaps in the slot, 251 as a deep safety and 191 as a box safety last season, according to Pro Football Focus. Along with Davis, Fitzpatrick should also provide stability in the leadership department for a defense that desperately needed someone to step up and do the same last season. 

Sweat, meanwhile, should upgrade the run defense by stepping into the middle of the line and clogging gaps up front. He is a mountain of a man at 6-4 and 366 pounds, and the only reason he was available to the Jets is that he wasn't really a fit for Saleh's attacking defensive scheme. Johnson was a better one. Sweat was PFF's fourth-highest graded run defender among 140 interior linemen who played at least 200 snaps last season, and he had only a 5.4% missed-tackle rate during his second NFL season.

Osa Odighizuwa, 49ers

Odighizuwa had the best years of his career playing on the same defensive line as Micah Parsons. He wasn't quite as good last year with Parsons having been sent from Dallas to Green Bay in the mind-boggling trade the Cowboys made before the season. 

Now, though, Odighizuwa will get to go play next to another elite edge rusher in Nick Bosa, who isn't quite Parsons when healthy but is pretty damn close. If Bosa is healthy, along with 2025 first-round pick Mykel Williams (who was playing well before suffering an injury of his own), the Niners have a very interesting defensive front. 

The 49ers built a defense last season that was far better than it had any right to be for much of the season, despite being under-talented and badly injured. Adding another high-level interior defensive lineman to the mix at the cost of just a late third-round pick is an intriguing proposition.