Patience and perseverance paid off for defensive end Mario Addison after an uneven start to what looked for the longest time like a journeyman career.

Consider that he has played 10 seasons, with 44 of his 60.0 career sacks coming in the last five.

Yet he heads into his 11th season under a cloud of uncertainty.

One of the many players the Buffalo Bills imported from coach Sean McDermott's former team, the Carolina Panthers, Addison didn't have the impact they were counting on when they signed him to a three-year, $30.45 million contract before the start of last season.

Addison finished with 5.0 sacks, which was good enough to tie for the team lead but was his lowest total since 2013, when he was still feeling his way on his fourth NFL team.

An adjustment that voided his final year but made his 2021 salary guaranteed followed, making it unlikely the Bills will move on until after this coming season.

It also means they'll be counting on him to bounce back at age 34 and help the defense take down opposing quarterbacks more than it did in 2020.

Thus, Addison slides in at 12th on our day-by-day presentation leading up to training camp of the 30 projected Most Valuable Bills for 2021.

In the meantime, the Bills aren't taking any chances. They used their first two picks of the 2021 NFL Draft on defensive ends, taking Miami's Gregory Rousseau at No. 30 overall and Wake Forest's Carlos "Boogie" Basham at No. 61.

They also brought in another former Panther, Efe Obada, to compete with the rookies along with A.J. Epenesa, Jerry Hughes, Darryl Johnson and Mike Love for what will be four rotational spots each week.

What the Bills also are counting on is for veterans like Addison and Hughes to show some of their younger players the way before stepping aside and allowing them to take over in what is expected to be a transitional season on the defensive line.

Will it happen the way they envision?

How this question is answered could go a long way toward determining whether the Bills will be able to take the next step and get to the Super Bowl after falling one game short last season.

More must-reads:

TODAY'S BEST
Cavaliers punch back, blowing out Celtics in Game 2
Coach: Oilers star center could miss Game 2 vs. Canucks
Watch: Cavaliers' Evan Mobley turns defense into offense in Game 2 vs. Celtics
Xander Schauffele tops stacked leaderboard after first round of Wells Fargo Championship
Rangers center making long-awaited return in Game 3 vs. Hurricanes
Suns talks with head-coaching target 'expected to move quickly'
Knicks get even more bad injury news ahead of Game 3
Frank Vogel fell victim to a Suns ownership group eager to win
2008 Celtics champion sentenced to prison despite emotional plea
Skip Bayless makes huge Tom Brady prediction after Netflix roast
14-year-old phenom signs unprecedented MLS deal that includes future Man City transfer
Pacers coach claims officials are biased against 'small market' teams
Hall of Famer makes bold prediction about Russell Wilson, Steelers
49ers Hall of Fame CB Jimmy Johnson dies
Rams make surprising move with former team captain
NBA announces discipline for Bucks' Patrick Beverley
Hall of Fame RB defends Najee Harris after Steelers decline fifth-year option
Pacers file shocking number of questionable calls after Game 2 loss vs. Knicks
Former NBA star says Anthony Edwards becomes face of the NBA if Wolves knock off Nuggets
Hornets hire top Celtics assistant as next head coach