What do the numbers next to the teams names on the Oakland A's out of town score board mean?

Answer 1

If the game is in progress the number is that of the pitcher currently pitching for the team. If the game is over the number is that of the pitcher who was credited with the win or loss for the team.

Answer 2

If the game is in progress the numbers are of the pitchers currently in the game. If the game is over, the numbers are the winning/losing pitcher of the game.