The Baltimore Ravens have signed David Olson following the injury to Joe Flacco.
Baltimore used offensive assistant coach Matt Weiss to line up under center and hand off to running backs in drills.
Olson will help spell Ryan Mallett, who has taken Flacco's spot with the first-team offense, and Dustin Vaughan, who is on his fourth team in four seasons.
The Ravens also have interest in Colin Kaepernick.
The agreement with Olson would not preclude the Ravens from adding Kaepernick.
Olson most recently played in the Champions Indoor Football league.