Williams (6 feet 3, 227 pounds) signed with the Ravens as an undrafted free agent in July. He played four seasons at Alabama, making 17 tackles in 33 career games.
The Ravens' linebacker depth has been challenged with Prescott Burgess going on season-ending injured reserve with a torn abdominal muscle Tuesday, and Dannell Ellerbe sidelined with a hamstring injury.
McCann signed a two-year deal with the Ravens in October while the team was dealing with several injuries in their secondary. However, rookie Jimmy Smith and veteran Chris Carr have returned to bolster the secondary, and David Reed has also come back from injury to handle kickoff returns, another area where McCann was used.
McCann was used sparingly, primarily working on special teams. He had two kickoff returns for 53 yards in the Ravens' 29-14 victory over the Houston Texans on Oct. 16, and had a special teams tackle a week later against the Jacksonville Jaguars.