The Ravens lost Ray Lewis to retirement and his "heir apparent" Dannell Ellerbe to free agency, and they were in desperate need of linebacker help. By selecting Arthur Brown, the Ravens get an extremely versatile player who can play any linebacker position.
Brown is your prototypical "tackling machine" who has a great nose for the ball. He sheds blocks very well and closes off running lanes before they can develop. Brown also defends the pass very well. I wouldn't expect Ray Lewis production from Brown, but the Ravens started the post-Ray Lewis era with a great pick.