I don't think you can point to any one factor.
The SF tackles obviously needed more than one game to get back up to speed. Reed is back in game shape and drawing attention. The secondary is playing much, much better than, for example, making Andy Dalton look like an All Pro in week one. The coaches are starting to trust the corners and the scheming is reflecting that. Perhaps, trusting that the safeties will provide proper deep help as well.
But more than anything, I think Clowney just had a very special night. To me, the most incredible part about the night was how much gas he had left in the tank in the late game. He was just as good in the 4th quarter/overtime as he was in the first half. Incredible stamina and "want to".