(Sorry Rengar.) Bard's roam potential is the main focus of his lane, so you want to try to chunk down your opponent and shove in the lane as much as possible in order to apply pressure in every lane at once.
This is because he's able to roam to either top or bot in the same amount of time from the mid lane, and he's the king of the jungle. Bard mid is functionally better than every other role.
