Atlanta has been eliminated from first place.

To show that Atlanta is eliminated from first place, we start with the current standings:
            Team	W	L	GL	PCT	GB
    Philadelphia	96	66	0	0.593	0.0
        New York	83	79	0	0.512	13.0
           Miami	79	83	0	0.488	17.0
         Atlanta	76	86	0	0.469	20.0
      Washington	66	96	0	0.407	30.0
           Total	400	410	0

Atlanta can finish the season with at most 76 + 0 = 76 wins and will finish the season behind the following teams:
Philadelphia has already won 96 games.
New York has already won 83 games.
Miami has already won 79 games.
# Atlanta Braves' magic number
# Atlanta's magic number
# Braves' magic number
# MLB Playoff Race