Baltimore Sun reporter Ken Murray ranks the best running backs in the NFL draft:1. Knowshon Moreno, Georgia: Only thing missing is breakaway speed. He's tough between the tackles, can maneuver in the open field and can catch.2. Chris Wells, Ohio State: Durability is the question with Wells. His physical running style led to a lot of injuries in college.3. Donald Brown, UConn: Patient runner with some explosiveness. He rates as a complete back.4. LeSean McCoy, Pittsburgh: Has cutback ability, but his size may make him a role player.5. Shonn Greene, Iowa: Hard runner who lacks speed.Ravens' needs: Although they appear well served with what they've got, they could go for a player who fits their system on the second day.Also see:.