I just heard Buster Olney on a local station here. When asked about the Sox, he mentioned the following factors for the sharp decline from last season: 1) Winner's fatigue (all the attention, events, interviews etc) 2) the let down in energy/efforts or hangover effect after getting to the top 3) Social Media's absorption, and the depression that follows 4) Some players on the Sox got paid and some did not, causing tension in the club house.
He also said that he was pretty shocked by Sale's contract, and believed it was a mistake, given all his physical issues. He emphasized that he still doesn't understand the thinking behind it. (Actually, I was under the impression that one of the five years was this year, so that makes it even more shocking to Me)