A few days ago, Levi gave us this current depth chart for the Raiders
The two spots that might be of special focus might be LG and RT. Even RG might be a worry with Brisiel. Parsons has been off and on the team since 2010 and showed some promise during each preseason. Bergstrom was found in Utah by Stefen's Uncle Steve in the Senior Bowl interviews. He was expected to do well in the ZBS scheme, but we aren't quite sure if he is ready to start.
With that said, there are two big names out there in RTs Smith and Vollmer who might come on a cheap deal. With the uncertainty of our QBs, WRs, and TEs, we do not know how well the air attack will go. Our best hope during this rebuilding stage would be to look to the running game and jump starting Run DMC. He cannot do that with three uncertainties on the offensive line.
The Oakland Raiders should look into these two FAs as soon as possible because although we are thin on the defensive side, we need to have some sort of upgrade on the offense. The game is won within the trenches.