The Oakland Raiders' playoff aspirations took a significant hit on Sunday night when they fell to the Dallas Cowboys in heart-wrenching fashion. Although the Raiders are not entirely out of the postseason picture, their chances are slim and their path has become more difficult with Pro Bowl left tackle Donald Penn declared out for the season due to his upcoming foot surgery, according to Ian Rapoport of the NFL Network.

Penn has been one of the most durable players at his position throughout much of his career. playing in every game since the start of the 2007 season when was a member of the Tampa Bay Buccaneers. His absence places a huge void on the left side of the offensive line, where he was primarily responsible for protecting quarterback Derek Carr's blindside.

This adds to what's been a frustrating season for the Raiders, who are 6-8 heading into Week 16. Following the team's first playoff appearance in 14 years, Oakland expected to take the next step in 2017 and become a potential Super Bowl contender in the AFC.

However, the team struggled with injuries in the early portion of the season, and Carr's inconsistent play cost them some winnable games. All of this sends the Raiders into the offseason looking to make changes to the roster to get them back on track.