I personally doubt that beating Sui/Han was the biggest factor; they skated after Sui/Han, they would have known that realistically they weren't going to be that score even with their few points' lead from the short.
KMT probably popped because she did it nationals and was thinking about not doing it again; with Michael, that sort of fall is flukey and the sort of thing that happens randomly.
Come on now. M-T/M were nearly able to take advantage of S/H's rustiness at last year's 4CCs. That's why I thought they were going to be able to manage to pull out a win this time. As I said, it had to be in M-T/M's minds that they needed to skate clean again in the fp. S/H laid down a very good fp and the judges responded, but they weren't perfect. Had M-T/M skated clean, they had a huge chance to do something special heading into Montreal Worlds, so it appears to me they put more pressure on themselves. I totally do not think M-T/M were thinking about coming in second or third at 4CCs after the sp they'd laid down w6ere they also skated after S/H and knew there was an opening.
Sure Mike's unexpected fall while skating forward was flukey because ice is slippery, and nerves sometimes make way for flukey missteps.
ETA:
Scoring 76.36 in the sp was a big score for M-T/M. Had they at least been as clean and on form in the fp, the judges might have been willing to reward them with additional high scores. The judges always like it when skaters perform reliably. With a clean free skate, it would not have been out of the realm of possibility for M-T/M to score around 72.27 (or slightly higher) on tech and 69.17 on PCS, which would have brought their combined scores in sp (76.36) and fp (141.44) to
217.80, which would have been enough to edge Sui/Han overall by percentage points.
S/H scored 144.34 in the fp and
217.51 overall. So in that scenario, S/H would have won the fp, but landed in second
behind M-T/M. Such a feat by Kirsten/Michael was totally possible with a clean free skate, especially seeing their huge sp score.