The Oakland Raiders have spent the majority of the 2013 offseason attempting to rebuild a defense that was torn down due to excessive contracts and under-performing starters.

The Raiders are only guaranteed to return two starters from 2013 in Tyvon Branch and Lamarr Houston. Second year linebacker Miles Burris was a starter in 2012, but with the influx of linebackers he will not have to compete for a starting spot in 2013.

Thus far, general manager Reggie McKenzie has addressed the majority of the holes on defense, completely overhauling the linebacker and defensive back units. There are still some depth concerns, but for the most part, the starting spots across both of those units are fairly set and in good shape.

The remaining hole on defense is the defensive line. Not just one position, not just pass rush, the entire line. The defensive tackle position is thin and does not have a single player who was a starter before 2013. There is a lot of young talent there, but no one has proven the ability to be a solid starter.

At defensive end the Raiders are also very thin. Houston is a clear starter and opposite him will likely be Andre Carter. Houston is a very solid player who can still be great if he keeps improving.  Carter was great in his day, but is on the back side of his career. He still has a lot to give, but he cannot play every down and still be effective.

But with all of that being said, the recent signing of Charles Woodson gives Raider Nation hope that McKenzie is not yet done shopping on the free agent market. The Raiders received more cap space over the weekend due to the June 1 designation given to Michael Huff when he was cut. While a lot of that will be used to sign draft picks, it is so late in free agency that there are deals to be had.

SedOf Pro Football Talk’s top 100 free agents, only 8 remain available. Of those eight, four are defensive linemen: Richard Seymour, John Abraham, Sedrick Ellis (pictured) and Israel Idonije. Seymour is a familiar name and will not likely be back in Oakland, but you never know given the lack of interest from other clubs.

John Abraham would be a dream for Raiders fans, but signing him is unlikely. He is clearly the best defensive lineman still available and would be a big upgrade to the Raiders’ almost non-existent pass rush. But since he can still contribute, he may not come as cheap as the Raiders would like.

Ellis and Idonije are both legitimate options. Neither should sign for a lot and both would add some depth and compete for starting roles. There are other defensive linemen available as well, though none as good as these.

However, another option remains. There are likely to be players who are cut by other teams that would help the Raiders. Teams like the Seattle Seahawks have so many defensive linemen that there is a chance a good player gets cut due to numbers, not talent.

At the end of the day, it is fairly likely that McKenzie will try and add a player or two to the defensive line. Most fans will root for one of the four guys mentioned above, but unless they are willing to come on very cheap, prove yourself deals, it is more likely that McKenzie tries to find a diamond in the rough from guys who are cut by other teams.