CINCINNATI — The Pittsburgh Steelers' December swoon is looking more like a collapse.The Steelers lost their third straight — getting thumped 27-17 by the last-place Cincinnati Bengals on Monday night — after ripping off 11 straight wins to start the season. They couldn't generate any offence early, and the opportunistic Bengals took advantage of their mistakes.Assured of a playoff berth, the Steelers (11-3) could have wrapped up the AFC North with a win but instead turned the ball over three times and allowed Cincinnati to build a 17-0 halftime lead.“We’ve got a lot of work to do,” Steelers coach Mike Tomlin said.