First, I ask why can't they continue this? Personally, I don't think they will, but I can't dismiss it as impossible.
The team OPS is .799, but it's been better 3 of the last 4 years, and the runs scored is pretty much right at the EqR or RC predictions. This is with 3 guys well below career averages and only 1 well above.
Only two pitchers have been pitching way over their heads, Wakefield and Okajima. Wake, while being a huge asset thus far, hasn't resulted in any extra wins. They are 4-5 in his starts. Jima won't keep this up, but who's to say if the runs he gives up result in losses. When/if relievers give up runs is random. Sometimes it coughs up the lead, sometimes it just reduces it.
Now, let's assume they don't keep it up for some reason. If they play .600 ball from here on out, they win 100 games. .580 gets them 98. .550 is good for 95. The Yankees have to play .680 ball for 101, .664 for 99, .639 for 96.
Bottom line, something bad needs to happen for the Sox to turn into a .500 or worse team, and if it doesn't, the Yankees need to play at about a 105 win pace to catch them.