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Khalil Mack has developed into a dominant pass-rushing force since the Oakland Raiders used the fifth overall pick on him in the 2014 draft, but they weren't able to reach a new deal with him and reportedly traded him to the Chicago Bears on Saturday.

Adam Schefter of ESPN provided a full breakdown of the trade:

NFL Network's Ian Rapoport added Mack and the Bears will immediately begin working on a contract:

Mack was set to be a free agent following the 2018 campaign before this news and held out for the entirety of training camp and the preseason in search of a new contract.

It reached a point that Manish Mehta of the New York Daily News reported "more than a dozen teams" asked about potential trades for Mack as his holdout continued.

The holdout came after Mike Florio of Pro Football Talk reported in December 2016 the defensive end's contract situation was intricately tied to that of teammate Derek Carr. Oakland selected the quarterback in the second round of the same draft it landed Mack, and each player was eligible for a new contract following the 2016 season.

However, he reported the Raiders were focused more on Carr than Mack at the time because they could extend the defender's four-year deal an additional year, as he was a first-round pick.

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In Carr's case, they would have needed to use the franchise tag to keep him off the market in 2018 if they didn't agree to a new deal. They ultimately signed the quarterback to a five-year extension before the 2017 season.

Mehta noted Mack was "looking to become the first non-quarterback to make $20 million per year." That is one expensive defender, but Mack has produced at a head-turning level since he entered the league.

He played all 16 games as a rookie in 2014 and notched 75 tackles and four sacks. He then became a Pro Bowler and First Team All-Pro member in 2015 with 77 tackles and 15 sacks. He followed that up with 73 tackles and 11 sacks as the Associated Press Defensive Player of the Year in 2016 and had 78 tackles and 10.5 sacks in 2017.

He also helped lead Oakland to the postseason for the first time in his career in the 2016 campaign and is still in the early stages of his prime with the potential to earn multiple Defensive Player of the Year awards throughout his career.

Mack will likely shift back to outside linebacker in Chicago's 3-4 defensive scheme and should further bolster a pass rush that finished seventh in the NFL with 42 sacks last season.