The Yankees need to make a push right here, right now, because the scheudule for the Red Sox going into the All-Star break is a relative cake-walk (at Baltimore (3), home vs. SEA(3), OAK(3) and KC(4)).  It is reasonable to assume that Boston wins all those series, going 9-4 in the process.

The Yankees play SEA (3) and Tor(4) at home and then play at Minnesota (3) and LAA (4).  So while the Red Sox have an easy trip to Baltimore then stay home until the break, the Yankees have a 4 game set against Toronto, then have to trek across the US to play Minnesota and a 4 game set against the Angels.  4 game series are tough to win.  So they need to sweep SEA (who is likely to lose Adrian Beltre) and at a minimum split the Tor and LAA series.  Then if they win the Min series, they finish 9-5 and ojnly lose a half game against Boston.  If they play like crap, they could be 6 out at the break.