I agree with the excellent work part, I think you did a really nice job as well. As you said in your Red Sox post, you're almost being a bit conservative, as weird as that may sound coming from a Yankee fan. If the Yankees continue to play as well as they are, I expect the Red Sox to really pick up the pace as well, and could possibly finish close to 100 wins.
As for the Yankees, it's all about whether they go on another one of those two weeks spirals from here on out. However, even if they continue to play extremely well, I think that their streak of division championships will end. The Yankees, in their current state, and considering the way they played in the first half, are probably right where you have them, a 90 win team. Still though, I think there are a couple things to consider that might push them over the 90 win mark and closer to 93 or 94 wins. Even with their subpar first half they had a winning record against plus .500 win teams. There two main problems in the first half were playing sub .500 teams and playing on the road. It seems like they've solved one of those issues, and hopefully the other will be solved in the near future. Now, we'll know soon if their good play against plus .500 teams continues, but if the first half is any kind of indicator, things should only improve.
In my opinion, there are three "X-factors" with this team, Phil Hughes, Joba Chamberlain, and Jason Giambi. This is pretty simple, in my opinion. All of them, except maybe Giambi, will have big roles on this team for the rest of the season. Their future performance this year, which is definitely a question mark, should be a determining factor.