$page = '<td>BOS @ ATL</td><td align="right"><a href="/news/game_preview.jsp?gid=2007_06_20_bosmlb_atlmlb_1">7:35 PM</a></td>';
              ^     ^
'BOS' can be in either of those places, but it has to be in one of them (i.e. ATL @ FUK shouldn't match)

$pattern = '#<td>BOS|([A-Z]{2,3}) @ BOS|([A-Z]{2,3})</td><td align="right"><a href="/news/game_preview.jsp?gid=([^"])*">#i';