I think there is retrospective reasoning being applied here, with respect, these are the arguments that were made after the event. I don't see how it's possible to argued it wasn't a shock when it so blatantly was. It was expected to win, it didn't - ergo it was a shock result.
I don't understand how you can argue it wasn't a shock when numerous sources at the time evidence that it was one!
I actually feel a bit sorry for Crash, tbh, winning did the film a lot of harm because the win was seen as tainted and it turned a lot of people off what was a pretty good film in it's own right.
With respect, they are arguments that it was entirely possible to make at the time. I think many people were blinded by how good Brokeback was and therefore assumed it would win as it deserved to, ignoring the high probability of the subject-matter not being one the Academy would favour. It wasn't a shock to me that it didn't win, so I can argue that it shouldn't be seen as a shock.