They are 4.5 back and this is their last chance to play the Sox heads up. If the status quo adheres, and the Sox take a game or two in the next couple of nights, the Yankees will more likely than not have to play a one-game playoff.
Whether intentionally or not, I think this is smart by C.C. A 4-game sweep and everything is in play. Why not give it a shot? It's the Sox who want low drama, nothing to see here baseball for the next three nights. It's the Yankees who could use a little maelstrom and distraction right now. Maybe it backfires. Maybe it's irrelevant. But what's to lose? Give it a shot, stoke up some emotions, get people worked up, and see what happens. The Sox are presently in the driver's seat -- see if you can't upset the apple cart.
Weird shit and drama happens with these teams. Emotions seems to actually matter. It may well be that C.C. isn't all that calculating and is just embarrassed, but even if unintentional, I don't see how this hurts the Yankees at the moment.