Every team has issues all year long that pop up and that they work on week-to-week to improve, while the opponent learns to counterpunch them. It's not just the Bills.
I wouldn't say we got clearly outplayed last night. We had areas where we struggled, sure, but we outgained them by 50 yards, won the T.O.P. battle by 5 minutes, and were a couple of inches away from a walk off win on enemy soil. Titans had some big plays break their way (kickoff penalty, 76 yard td run, PI/helmet catch, etc.). It happens. Especially against playoff teams on the road. The Patriots won 6 Super Bowls and they didn't go undefeated in any of those years as far as I can recall.