The Oakland Raiders will need to do a lot of work on their offensive line. Probably their worst unit on offense or defense last season, the Raiders offensive line was comprised of street free agents and undrafted free agents. Injuries plagued the unit and prevented and hope of having a successful season.
In order to avoid another disaster like the 2013 season, the Raiders will need to massively improve their offensive line, from the starters to the back ups. Even if the Raiders bring in free agent offensive lineman, they will likely draft one or two as well. They can use young talent for added depth and give them time to develop. Some guys in the draft would automatically be an upgrade over some of the Raiders interior lineman.
Most of the instant starters would come in higher rounds and the Raiders may not want to invest in the guard position that high. Clearly this depends a lot on how the free agent period plays out for the Raiders. If they can plug a lot of holes, it will give them the opportunity to pick guys regardless of need.
But even with an immense amount of cap space, the Raiders will be hard pressed to fill every hole through free agency. Plus, general manager Reggie McKenzie is a firm believer in building through the NFL Draft and will likely look to the first few rounds as picks with the potential to fill big holes right away (as he should).
Regardless of the strategy used when attacking the offensive line deficiencies this off season, the Raiders are highly likely to take at least one interior lineman during the draft. For a little more info on the guys who could be chosen, take a look at the cover32 top ten interior linemen list.