Oakland Raiders quarterback Derek Carr enjoyed a true breakout season this past year, his second in the NFL. The young QB saw upticks in his completion percentage (61.1), passing yards (3,987), touchdowns (32) and average yards per pass (6.96) as the Raiders made major strides on offense. Left tackle Donald Penn, and the offensive line as a whole, were major contributing factors in Carr's impressive sophomore campaign. Oakland allowed just 33 sacks and 64 QB hits on the season, ranking in the top half for both categories. However, Penn may be elsewhere for the 2016 season.

Jerry McDonald of Inside Bay Area noted that the pending free-agent left tackle removed all mentions and references to the Raiders from his social media accounts this past weekend. This would seem to suggest that the 32-year-old veteran is planning on joining a new team this offseason.

Penn went undrafted in 2006 before signing on with the Minnesota Vikings. He was released after just one season. He then spent seven years with the Tampa Bay Buccaneers, making one Pro Bowl, before being released again. However, Penn's two seasons with Oakland proved that he has plenty left in the tank. Pro Football Focus ranked him 10th out of 76 qualifying tackles in 2015 and seventh out of 84 qualifiers in 2014.

Given his career resurgence, Penn is looking for a significant pay raise after completing his two-year deal worth $14.3 million with the Raiders. Oakland may want to go younger at the position, but they are expected to have roughly $50 million in salary cap space in case they do want to re-sign their blind side blocker.

Potential replacements that could be found on the open market include Russell Okung (28), Cordy Glenn (26), Donald Stephenson (27) and Sam Young (28). The Raiders also hold the No. 14 overall pick in the 2016 NFL Draft, though they are expected to target a defensive player with that selection.