Ravens sign Thad Lewis, waive Dustin Vaughan

OWINGS MILLS, Md. -- The Baltimore Ravens added an experienced arm for training camp, signing journeyman quarterback Thad Lewis on Monday.

Lewis is the latest quarterback to be signed by the Ravens since the team said it was considering signing controversial free agent Colin Kaepernick.

The Ravens have been shuffling quarterbacks all summer behind Ryan Mallett, who is filling in for the injured Joe Flacco. Baltimore has signed three quarterbacks since training camp began.

Lewis, 29, has played for seven teams over the past seven seasons, compiling a 2-4 record as a starter. He hasn't thrown a pass in a regular-season game since 2013, but he's had more extensive work than Dustin Vaughan, who was released by Baltimore on Monday.

The Ravens brought in Lewis after Vaughan struggled in Thursday's preseason opener and dropped to the bottom of the depth chart. Baltimore will go with Mallett, Lewis and Josh Woodrum in Thursday's preseason game at Miami.

Flacco won't play in the preseason because of a back issue but is expected to be ready to start the Sept. 10 regular-season opener in Cincinnati.