Williams, who is now lost for the season with a neck injury, totaled 13 tackles in seven games this year.
Hogan has spent the first part of the season on the PUP list while recovering from knee surgery. The West Virginia product, taken in the fourth round of this year's draft, suffered a torn anterior cruciate ligament in the Mountaineers' 2010 regular season finale.
Keiser was signed to the practice squad on September 6 after being waived by the club two days prior. He was signed as an undrafted free agent out of Stanford in July.