If the Red Sox play .500 ball the rest of the way, they still win 93 games. To match that total, the Yankees would have to go 35-19, nearly .650 ball. The Yanks are capable of doing that, but they'd have to do it while the Red Sox lost. Considering the Sox still have 12 against Tampa Bay and 10 against Baltimore, that's going to be tough.
Can it be done? Absolutely. Just doesn't seem likely.
Now the wild card- that's another story entirely.