Under old head coach Doug Marrone, the Bills’ defensive line wasn’t just the best part of the team’s defense. It was the strength of the roster as a whole. It was also on the verge of becoming very, very expensive.

Defensive end Mario Williams was already one of the league’s highest-paid players, with a cap hit of $19.4MM due for 2015. Fellow defensive end Jerry Hughes was on his way to a payday of his own, and landed a $45MM extension in March. Meanwhile, defensive tackles Marcell Dareus and Kyle Williams were in line for the club’s second- and third-highest 2015 cap numbers.

The arrival of Rex Ryan and new defensive coordinator Dennis Thurman doesn’t make any of those players any less expensive, but a new defensive scheme should spread those big salaries out a little among the front seven. Rather than four defensive linemen being among the Bills’ five largest cap charges of 2015, two of those players – Hughes and Mario Williams – now figure to line up at the outside linebacker position most of the time in Thurman’s 3-4 defense.

Had those four standout players remained on the defensive line, the Bills would have had to decide whether to commit a huge chunk of their salary cap to one position group, and it looked as if the team was prepared to do just that. Certainly, if one of the four were to walk in free agency, it would have been Hughes, the only one in the group who hasn’t earned a Pro Bowl nod. Hughes, who has recorded double-digit sacks in each of the last two seasons, can hold his own against the run, but he’s essentially a pass-rushing specialist, and the club was still willing to lock him up for $9MM per year.

That deal bodes well for Dareus, the last member of the Bills’ old 4-3 line eligible for a big payday. Because he was a first-round pick, the former Crimston Tide star had a fifth-year option on his four-year rookie contract, which the Bills exercised a year ago, keeping the All-Pro lineman under team control through the 2015 season. While that bought the club a little extra time, Dareus’ contract will have to be addressed soon, or else he’ll be eligible to be franchised or to hit the open market in 2016.

A defensive tackle under Marrone, Dareus appears likely to continue playing on the inside under Ryan, occupying the nose tackle role in Thurmond’s 3-4 scheme. Interior defensive linemen typically don’t post huge sack numbers, but Dareus has done an impressive job getting after the quarterback in his first four seasons, recording 28.5 career sacks, including 10 in 2014, a total that matched Hughes’ output. That number may decline for the first time in 2015 as Dareus moves to nose tackle, but the Bills value his ability to stop the run at least as much as his ability to bring down the quarterback.

Without extensively studying Dareus’ game tape, his overall impact against opposing run games is hard to quantify, particularly since the Bills were outside of the top 10 run defenses in 2014, allowing 106.4 yards per game and 4.1 yards per carry. However, Pro Football Focus (subscription required) ranked Dareus first among the league’s defensive tackles as a run defender, giving him a +20.7 grade. By comparison, Ndamukong Suh was second, with a +17.6 mark.

At age 25, Dareus is several years younger than Mario Williams or Kyle Williams, who are both in their 30s, and he’s a more dynamic and well-rounded defender than Hughes. Coming off his first All-Pro nod, the former third overall pick appears poised for a massive payday. The only thing that might derail it? Some dreaded “off-field concerns.”

The term “off-field concerns” has become a catch-all that can refer to anything from possible mental health issues to a serious criminal record. In Dareus’ case, those “concerns” date back to a pair of arrests that occurred during the 2014 offseason — one for possession of a controlled substance and drug paraphernalia, and another for endangerment and leaving the scene of an accident.

Dareus is facing a one-game suspension for his drug arrest, meaning he’ll miss the Bills’ regular season opener in 2015. While one missed game isn’t a huge concern, and probably won’t have a major impact on the team’s willingness to extend the star defensive tackle, it’s a red flag, since any subsequent violations would result in longer and costlier suspensions. I don’t think that risk will deter the Bills from making Dareus one of the highest-paid defensive linemen in the NFL, but the club may include language in the 25-year-old’s next contract that protects the franchise if he’s arrested again.

So what sort of years and dollars might Dareus be looking at on his next contract? He and his reps may point to Suh’s deal and argue that Dareus has been just as effective as the former Lion. But Suh joined the Dolphins as an unrestricted free agent, and Dareus would be hard-pressed to match those numbers even if he reached the open market, which won’t happen anytime soon. It’s too early to know exactly what the 2016 franchise tag figures will look like, but it would likely cost Buffalo about $12MM to franchise Dareus, which looks like a nice bargain compared to the $19MM+ annual salary Suh is earning in Miami.

It’s more likely that Dareus’ extension comes in at a price closer to what Gerald McCoy got from the Buccaneers. McCoy’s seven-year pact was worth $95.2MM, an average of $13.6MM per season, which could go as high as $14MM per year via incentives. With the salary cap on the rise, there’s a chance Dareus exceeds that annual salary, but I think it’s more likely that he settles for a bit less. Based on how Tampa Bay’s front office structures contracts, McCoy’s extension didn’t include a ton of guaranteed money, whereas the Bills are more likely to include sizable signing bonuses and option bonuses in their deals.

If Dareus were to accept a multiyear extension worth in the neighborhood of $12-13MM per year, the team could be happy knowing that it will pay its star defensive tackle less money per year than the Bucs are paying McCoy, and significantly less than Suh or J.J. Watt are getting from their respective teams, which could help assuage those “off-field concerns.” At the same time, Dareus could land a guarantee that’s more significant than what McCoy got from the Bucs, which would make it more difficult for the Bills to move on from him within the first two or three years of the contract.

If Dareus’ legal run-ins are a serious concern for the Bills, or if Suh’s mammoth new contract has increased Dareus’ asking price significantly, it’s possible these contract talks will extend into 2016, perhaps necessitating the use of a franchise tag. However, GM Doug Whaley has stressed that working out a long-term agreement with Dareus is the Bills’ top priority this summer, so I expect we’ll see the two sides get something done before the season begins.

What do you think? Will the Bills and Dareus reach a deal soon? What’s your salary estimate for his next contract?

Photo courtesy of USA Today Sports Images.