All three players are valuable retentions by the team.
Parson is the primary backup behind Stefen Wisniewski at center. He started the Raiders season opener last season while Wisniewski was still recovering from a torn labrum that required off-season surgery. Parsons also backs up at guard. The team originally signed him as an undrafted free agent out of USC in 2011.
Ross was a tremendous find for this staff last season. They signed him off the Packers' practice squad during the season and he stepped up for the team and their depleted secondary. He is expected to compete with newly signed Usama Young to replace the departed Michael Huff at free safety.
Stewart leapfrogged Taiwan Jones last season to get carries when both Darren McFadden and Mike Goodson were injured. The undrafted rookie out of Stanford appeared in four games, carrying the ball 25 times for 101 yards (4.0 yards per carry). With Goodson leaving as a free agent, Stewart remains much needed depth.
The team had previously announced signing ERFA's Coye Francies and Kaelin Burnett. This means the Raiders have just two unsigned exclusive right free agents - WR Duke Calhoun, and OT Zach Hurd. Neither player is listed on the team's roster.