The Seattle Seahawks led the NFL in fewest points allowed for the fourth straight season in 2015.
But they go into this offseason with four defensive starters set to test free agency, including three in the front seven.
Below is a position-by-position breakdown of where things stand with the Seahawks' defense and where they might spend their money. The priority scale goes from one to five, with a five meaning the position must be addressed in the weeks ahead.
Two of the Seahawks' four starters -- defensive tackles Brandon Mebane and Ahtyba Rubin -- are unrestricted free agents. Neither player gained a lot of notoriety during the 2015 season, but both were critical to the team's stout run defense, which limited opponents to 3.6 YPC. Given that Mebane and Rubin are primarily two-down players, it will be interesting to see what kind of market develops for their services.
If one or both sign elsewhere, look for the Seahawks to add a defensive tackle or two. The method here in previous years has been to find veterans who can serve as cost-effective, short-term fill-ins, and that could continue once again this time around.
It's worth noting that there are several defensive linemen on the market who have previously spent time with the Seahawks such as Jason Jones, Tony McDaniel and Sealver Siliga. It's possible the Seahawks try to bring one of those players back.
It seems likely Bruce Irvin will be moving on. Irvin played a versatile role with the Seahawks, serving as an outside linebacker in their base look and moving to defensive end in nickel. The truth is there aren't a lot of athletes capable of filling that dual role. The Seahawks may need to go with someone like Kevin Pierre-Louis in their base defense and then replace him with a pass-rusher in sub packages.
Assuming Irvin moves on, a couple names who could fit: Courtney Upshaw of the Baltimore Ravens and Nick Perry of the Green Bay Packers. Upshaw has been a disappointment as a pass-rusher, but he can play the run and is experienced in coverage.
Perry is a great athlete and played his college ball at USC. He could play defensive end in the Seahawks' sub package and also back up Cliff Avril at the Leo spot.
When the Seahawks cut Cary Williams during the 2015 season, many in the building -- including coach Pete Carroll and Richard Sherman -- pointed out that it's difficult to get veteran corners who have played in other systems to perfect the team's step-kick technique.
The Seahawks signed Williams to a three-year, $18 million deal ($7 million guaranteed) last offseason, but don't expect them to go that route again. Instead, expect a push to bring Jeremy Lane back. He's been in the system for four years. He's played both outside and inside. And he'll be just 26 when next season starts.
Given how respected Seahawks defensive backs are league-wide, Lane will have a market. But it makes sense for the team to try to bring him back. If he signs elsewhere, the Seahawks likely won't spend on another corner. They can take their chances with DeShawn Shead and try to develop some of the younger guys on the roster, such as Tye Smith.
The Seahawks have to figure out if they're going to do anything with Kam Chancellor's contract, and Chancellor will have to decide if he's going to hold out again. But given that a trade seems unlikely, the expectation here is that he'll be back.
Earl Thomas is the free safety, and the team addressed depth before the season, trading for Kelcie McCray. Shead is a restricted free agent, and the Seahawks should be able to bring him back. He has the versatility to play both corner and safety.
In other words, this is not a need position, and don't expect the Seahawks to make a move.