Hull's signing comes on the heels of the team losing special teamer and backup linebacker Bryan Kehl, who tore his ACL Sunday night versus the Cowboys. Hull will likely resume Kehl's post, and add depth to the linebacking corps and special teams.
The Redskins also lost long snapper Nick Sundberg for the season due to a torn meniscus. No subsequent signing has yet been made to replace him.
Hull was a seventh-round draft pick in 2010 out of Penn State, and has recorded 11 total tackles and two forced fumbles in 28 games.
(h/t Adam Caplan)