Free agency in the NFL might be a dud this year. All of the action is taking place before free agency even starts.

The 2018 season officially kicks off at 4 p.m. on Wednesday, opening the doors to free agency, trades, and a flurry of activity across the league.

But NFL general managers aren’t just sitting on their hands waiting for Wednesday — especially Browns GM John Dorsey and Rams GM Les Snead. Trades can’t become official until 4 p.m. on Wednesday, but several high-impact trades and releases have already been agreed to. Richard Sherman, Tyrod Taylor, Jarvis Landry, Michael Bennett, Danny Shelton, Aqib Talib, Marcus Peters, Robert Quinn, Alec Ogletree, Damarious Randall, and DeShone Kizer will all be wearing new uniforms come Wednesday.

By Wednesday, most of the top players may be off the market, but free agency should still be a fascinating game of musical chairs at quarterback, where Kirk Cousins and Drew Brees are the most important dominoes.

As of Friday afternoon, there was $1.025 billion in salary-cap space among the 32 teams, per the NFL Players Association. And that number doesn’t take into account several cost-cutting moves that occurred last week (such as the Martellus Bennett release) and the many more that will happen over the next few days.

Let’s take a look at the latest buzz in free agency:

■ The expectation remains that Brees will re-sign with the Saints, but the fact that he and the Saints still haven’t agreed to a new contract is a situation that bears monitoring.

Otherwise, Cousins is the top player available, and he’s the linchpin. The quarterback market won’t move until Cousins makes his decision.

■ Cousins has narrowed his market to four teams — the Vikings, Broncos, Jets, and Cardinals. The Jets can offer him the most money. The Vikings and Broncos offer him the best chance to win now. The Cardinals are a bit of a wild card — they appear to be in rebuilding mode and don’t have a ton of cap space ($20.6 million or so), but it could be mighty tempting to throw passes to Larry Fitzgerald and hand off to David Johnson.

■ The Bills don’t have a quarterback after trading Taylor to the Browns, and with about $40 million in cap space now, they could be contenders for Cousins. The Bills also have a ton of draft capital — picks 21 and 22 in the first round, 53 and 56 in the second round, and 65 and 96 in the third round.

If they draft a quarterback, the Bills will also need to sign a QB in free agency, someone of the A.J. McCarron/Sam Bradford/Mike Glennon variety for $10 million to $12 million.

■ The Vikings told Teddy Bridgewater at the Combine last weekend that they intend to pursue Cousins, per a league source, but that Bridgewater remains a viable backup plan.

And the Vikings have a couple of issues in going after Cousins. One is that the Vikings want to do new contracts for Stefon Diggs, Anthony Barr, and Danielle Hunter, and giving a mega-deal to Cousins could complicate that. The NFL’s funding requirement could also be an issue — teams are required to put all guaranteed money into escrow, and Vikings ownership isn’t wealthy enough to simply cut a $90 million check and be done with it.

■ The Broncos need a quarterback and a left tackle, and while they should make a run at Colorado native Nate Solder, who is the only starting-caliber left tackle available in free agency, they’re more likely going to have to find one in the draft. They’re also more likely to find a quarterback in free agency.

If the Broncos don’t land Cousins, a good backup option is Case Keenum, who is coming off a career year in Minnesota. Gary Kubiak, now a senior personnel advisor in Denver, signed Keenum as an undrafted rookie for the Texans in 2012 and coached Keenum for his first two years in the league.

Former first-round pick Paxton Lynch has two more years to prove himself, and Keenum can likely be had for $16 million-$18 million per year.

■ Trading for Taylor takes the Browns out of the discussion for McCarron or any other veteran backup, and should likely squash any talk of them going after Cousins. But the Browns have their seat-holder now, and can focus on finding their future QB in the draft. Despite all the hype about Penn State running back Saquon Barkley, the Browns should still take a quarterback with the No. 1 overall pick.

■ But the Browns, Jets, Vikings, Broncos, and Cardinals aren’t the only teams looking for a veteran quarterback. Per a league source, the Dolphins, Jaguars, and Panthers also are heavily interested in finding a veteran QB this offseason.

The Panthers simply want an upgrade to Derek Anderson given the physical playing style of Cam Newton, who has only missed three games in seven seasons but is constantly banged up.

The Jaguars gave Blake Bortles a new three-year contract, but it’s really only a two-year deal, and they know that Bortles could easily regress in 2018. They are in win-now mode and want someone who can push Bortles, or take over if Bortles falls off a cliff.

And the Dolphins are in must-win mode after a disappointing 6-10 season. Ryan Tannehill has missed 19 games over the last two seasons, and does not have much support in the front office, though Adam Gase and the coaching staff do like him, per a league source.

The Dolphins have invested a ton of money into the defense — Ndamukong Suh, Cameron Wake, Reshad Jones, and others — and the trade with the Rams for Quinn again demonstrates that they’re going for it in 2018, not rebuilding. So a veteran backup QB makes a lot more sense than the buzz that the Dolphins are going to draft one in the first round.

“Why would they draft someone for the next guys?’’ said the league source, referring to the next GM and head coach.

■ To that end, Bridgewater should be in high demand between the Dolphins, Jaguars, and whichever teams lose out in the Cousins sweepstakes. Bridgewater won’t be handed a starting job, but he should command $12 million-$15 million per year on a one- or two-year prove-it deal.

■ NFL teams love Bradford, and he also should find a home shortly after Cousins signs. The problem is Bradford’s left knee, which knocked him out for most of last season. Bradford has become a professional placeholder, and can keep a team afloat while they figure out their long-term plans. But his knee will prevent him from signing anything more than a short-term, prove-it deal.

■ The best free agents remaining in a weak crop (in no particular order): Solder, RB Dion Lewis, WR Allen Robinson, WR Sammy Watkins, G Andrew Norwell, DE Sheldon Richardson, DT Dontari Poe, DE Muhammad Wilkerson, DT Bennie Logan, LB NaVorro Bowman, CB Trumaine Johnson, CB Kyle Fuller, and CB Malcolm Butler.

■ The hottest free agent you’ve never heard of: Norwell, who started 45 of 48 games the last three years for Carolina. Expect a bidding war between the Giants and Cardinals, who should be fighting over all of the Panthers’ free agents. Giants GM Dave Gettleman and Cardinals coach Steve Wilks both came from Carolina.

■ Sherman’s release created a lot of buzz in New England, but he seemed more like a luxury than a necessity for the Patriots, who have much bigger needs in the front seven.

Sherman reportedly reached agreement on a three-year deal Saturday with the 49ers, who have a ton of cap space, a need at cornerback, and their defensive coordinator is Robert Saleh, who coached for the Seahawks during Sherman’s first three seasons. The Chargers could have given Sherman a chance to play in his hometown, and their defensive coordinator is Gus Bradley, who coached Sherman in Seattle and employs the same scheme.

DISRUPTIVE FORCE

One man’s way to evaluate defense

Anyone who knows football knows that the sack statistic is an incomplete and often misleading way to evaluate the performance of a defensive front seven.

So last week, we came up with a new metric called “defensive disruptions’’ — adding up the number of sacks, run stuffs, tackles for loss, safeties, and quarterback hits. It’s still an imperfect statistic, as it doesn’t quantify the increased importance of a sack or a tackle for loss over a QB hit. But “defensive disruptions’’ still seems like a better way to evaluate the performance of a front-seven player rather than simply counting up his sacks.

Here’s what we found:

■ The Patriots, not surprisingly, ranked near the bottom of the league in most stats. They were 27th in total disruptions (228), ahead of only Kansas City, Oakland, Indianapolis, Tampa Bay, and the Giants. While the Patriots tied for seventh with 42 sacks, they finished 17th in quarterback hits, 31st in run stuffs, and 32nd in tackles for loss. The Patriots did face the third-most pass attempts and fifth-fewest rush attempts in the NFL, which partially explains some of the numbers.

■ Trey Flowers was by far the Patriots’ most disruptive player, with 42 in 14 games, ranking 28th among all defensive players. Deatrich Wise was second with 30 disruptions in 16 games, and Kyle Van Noy had 25 in 13 games. Flowers led the Patriots in sacks (6.5, tied for 46th in the NFL), tackles for loss (8, tied for 74th), and quarterback hits (25, tied for seventh). Lawrence Guy led the Patriots in run stuffs (5, tied for 61st).

■ In January I wrote that I would give my fictitious Defensive Player of the Year vote to Aaron Donald, but now I would change it to Chandler Jones. The former Patriots defensive end had an unbelievable year in Arizona. Jones’s 89 disruptions put him in a class by himself in 2017.

Rounding out the top five: Jadeveon Clowney (64.5), Calais Campbell (63.5), Cameron Jordan (61), and Melvin Ingram and Donald (59.5).

Jones’s 17 sacks led the league by 2.5. His 33 quarterback hits led the league by three. His 28 tackles for loss led the league by seven. And his 11 stuffed runs were third most in the NFL (Clowney led with 13).

The most disruptive defenses: Pittsburgh (303), Philadelphia (293), Dallas (288), Jacksonville (287), and, believe it or not, Cleveland (284).

On a per-pass basis, the best teams at hitting the quarterback were: Pittsburgh (.208 hits per pass attempt), Jacksonville (.206), Washington (.203), Seattle (.200), and Carolina (.191). The Patriots finished 20th (.158).

ETC.

Gillislee, Dorsett may be returning

■ Nothing is set in stone yet, but a league source says signs are looking good for running back Mike Gillislee and receiver Phillip Dorsett getting another shot with the Patriots in 2018. Neither player did much last season — Gillislee rushed for just 383 yards in nine games and was a healthy scratch for the second half of the season, while Dorsett caught just 12 passes for 194 yards in the regular season. But both are cheap (Gillislee $1.9 million salary, Dorsett $1.544 million), so it’s worth keeping them around to see how they fit in next season. Dorsett has a $450,000 roster bonus due on the fifth day of training camp, so that appears to be the key date for his future.

■ Special teams ace Nate Ebner is a free agent and recently switched agents, signing on with Neil Cornrich, who used to be Bill Belichick’s agent before Belichick started negotiating his own contracts. Cornrich also represents Trey Flowers, James Ferentz, Rex Burkhead, and Cole Croston.

■ The Patriots don’t have an assistant special teams coach anymore after Ray Ventrone left to join Frank Reich’s staff in Indianapolis. Assistant special teams coach seems like the perfect gig for Brian Belichick, the coach’s youngest son who has been a scouting assistant for the last few seasons. Belichick’s other son, Steve, is the safeties coach.

Stills goes above and beyond

Hundreds of NFL players help their communities with their foundations and charity work, but few players do it in such a hands-on fashion as Kenny Stills of the Dolphins.

Stills spent two weeks touring the south and participating in various social justice projects. He went to Tallahassee, Fla., to join protestors for fair treatment of incarcerated individuals. He participated in a women’s march in Charlotte. He spoke with at-risk high school kids in Lexington, Ky., and Memphis. He participated in a “know your rights’’ camp with Colin Kaepernick in New Orleans. He shared photos of civil rights activistMedgar Evers’s home in Jackson, Miss., did a literacy program with kids in Birmingham, Ala., walked the Edmund Pettus Bridge in Selma, Ala., and spoke about social justice in Montgomery, Ala.

“One of my biggest takeaways is how valuable our time is to others,’’ Stills wrote on Twitter. “Next time you go to write a check think about volunteering your time instead. Mentorship is the most direct route to impacting the next generation.’’

Extra points

The salary cap came in at $177.2 million for the 2018 season, slightly under the projection of $178 million-$180 million. The cap “only’’ increased by $10 million this year, as opposed to $12 million in each of the previous two seasons. But it’s not because revenues were down last year. Per Pro Football Talk, the NFL and NFLPA agreed to lower the cap slightly and instead increase the Player Performance Pool, a pool of bonus money that rewards lower-paid players who outperform their contracts. Each team will have $4.415 million to pay out to players based on playing time in 2017 . . . Former Raiders coach Jack Del Rio made a good point on Twitter last week following the release of Aldon Smith. “Never liked ‘league rules’ that eliminate the ability of teams to offer Aldon and others in his situation the structure they so desperately need,’’ Del Rio said. Smith has had well-documented problems with substance abuse and DUI arrests, yet league rules forced him to not have any contact with the Raiders during his suspensions instead of allowing him to be with the team and get the structure he so badly needed . . . Self-representation is getting popular these days. Richard Sherman is acting as his own agent as he sets up free agent visits and negotiates a contract, and draft prospect Lamar Jackson is also forgoing an agent, using his mother as a front person instead. The NFL Players Association provides plenty of resources for players to negotiate their own way, but agents can definitely help. Sherman wasn’t able to speak with other teams and gauge the market for his services at the Combine, like agents do. And Jackson isn’t being getting the polish he needs, as a source said he didn’t do well in interviews and white-board work at the Combine. An agent can help put the right people around a young player.

Ben Volin can be reached at ben.volin@globe.com. Follow him on Twitter @BenVolin. Material from interviews, wire services, other beat writers, and league and team sources was used in this report.