San Francisco has been eliminated from first place.

To show that San Francisco is eliminated from first place, we start with the current standings:
            Team	W	L	GL	PCT	GB
     Los Angeles	98	64	0	0.605	0.0
       San Diego	93	69	0	0.574	5.0
         Arizona	89	73	0	0.549	9.0
   San Francisco	80	82	0	0.494	18.0
        Colorado	61	101	0	0.377	37.0
           Total	421	389	0

San Francisco can finish the season with at most 80 + 0 = 80 wins and will finish the season behind the following teams:
Los Angeles has already won 98 games.
San Diego has already won 93 games.
Arizona has already won 89 games.
# San Francisco Giants' magic number
# San Francisco's magic number
# Giants' magic number
# MLB Playoff Race