Cardinals safety Tony Jefferson recovers a fumble last week against the Buccaneers.

Tony Jefferson wishes he could hibernate during the months when the NFL switches from a game to a business.

The Cardinals' fourth-year safety is off to a tremendous start in 2016, leading the team in tackles (21) and tackles for loss (4) while grading out as the second-best safety in the league through two games by Pro Football Focus.

He has taken over for the departed Rashad Johnson and played every snap as the starting strong safety, an ascension which is of little surprise to him.

This is the player Jefferson expected to be when he left Oklahoma in 2013, although no one drafted him. This is the player he knew he was when he hit restricted free agency this March, although the Cardinals gave him the lowest tender and no other team signed him to an offer sheet.

If only every week of the year was a game week.

"I hate free agency," Jefferson said. "I hate all that. If it was a perfect world, I wish we could all just stay with the team where you go. Obviously it doesn't work that way. Obviously I didn't get what I wanted this offseason, so that does fuel me -- still being overlooked and undervalued. It's my year to show."

The pending unrestricted free agent has proven plenty so far, taking over as a chief play-maker in the secondary as safety Tyrann Mathieu returns slowly from a torn ACL. Jefferson has been around the ball constantly, recovering a fumble, bringing down ballcarriers and even harassing quarterbacks on the blitz.

"I'm honestly just going out there playing football a lot smarter than I have been and a lot more aggressive than I have been," Jefferson said. "I just feel more comfortable."

Much of that came from his offseason preparation. Jefferson dropped weight to get faster and dropped social media to study more.

"I've always thought he was a great tackler; I've always thought he was underrated in coverage," Mathieu said. "I think he's really putting it all together this year. He had a great offseason. I think he's got like six percent body fat, so he's been really focused. It's a big year for him. A contract year, he's got a son now -- he's got a lot of different things motivating him."

Jefferson is aware of the pivotal offseason coming up, but now he's back in the comfort zone of the regular season, focused on the jewelry he can earn regardless of the size of his next contract.

"I'm happy, beyond blessed, to be in the situation I am now," Jefferson said. "I worked my tail off, and it's only been two games so I'm not getting hung up on what the stats are now. I'm just trying to get a Super Bowl ring and do what I can do to help this team."

EVAN MATHIS WON'T PLAY AGAINST BILLS

Right guard Evan Mathis has been ruled out of Sunday's game because of a turf toe injury. He will be replaced in the starting lineup by Earl Watford, who coach Bruce Arians said looked "solid" in practice this week.

Defensive tackle Frostee Rucker (knee) and outside linebacker Kareem Martin (knee) are doubtful. Defensive tackle Robert Nkemdiche (ankle) and cornerback Justin Bethel (foot) are listed as questionable.

For the Bills, star wideout Sammy Watkins (foot) is listed as questionable, but coach Rex Ryan felt pessimistic about his availability when talking to the Buffalo media on Friday. Left tackle Cordy Glenn (ankle) and safety Colt Anderson (foot) won't play.

 Tight end Charles Clay (knee), cornerback Ronald Darby (hamstring), quarterback Cardale Jones (shoulder) and wideout Greg Salas (groin) are questionable.

CARDINALS PREPARE TO FACE NEW OFFENSIVE COORDINATOR

The Bills have struggled to sustain drives during their 0-2 start, and as a result, offensive coordinator Greg Roman was fired after last Thursday's 37-31 loss to the Jets.

Running backs coach Anthony Lynn was chosen as his replacement, but the Cardinals don't expect to see anything drastically different. The Bills have spoken this week of making the offense simpler, but their strengths remain their strengths.

"Their M.O., as we know from last season, is to run the ball and run the ball well, "defensive coordinator James Bettcher said. "To be physical in the run game… and then they try to throw the ball over the top of your head. We don't anticipate that to change. How they run the ball, how they throw the ball and distribute it, as the course of the game goes we'll figure those things out and adjust to them."

The Bills could opt to be even more run-heavy on Sunday if Watkins doesn't play.