The alternate reality thing was probably just too tempting to pass up. After a season told chiefly in flashbacks,then a season of flashforwards,they couldn't resist a season of,as someone coined,flashsidewards. Didn't Faraday decide shortly before his mom plugged him that things in the past could be altered after all because people utilizing free will were an uncontrollable variable? It'll be interesting to see what Sawyer will do now that he's lost everything that mattered and owes allegiance to nobody. That is,if he's not saddled with Kate in short order.