I don't like the term flop. The Vita was a flop, the WiiU is a flop. Titanfall is not a flop.It's not a flop, the game itself sold very well (but who doubted otherwise). The reason people are calling it a flop is because it failed to do what it was supposed to. MS was banking everything on it, they spent millions on advertisements, the press yapped on and on about it and X1, they even issued unofficial price cuts to go along with it and yet not only did it not beat the PS4 (which was a good amount ahead), it actually sold less per week than in Feb.
That's the very definition of failure, and there's no way MS is happy with it.
Turns out it's a good, but run of the mill FPS, and not the revolutionary, ground breaking game it was hyped up to be.
I think we should stay level headed here and call Titanfall not matching expectations.