Yeah I think what's so hard to take, or to make sense of, is that ultimately it's the almost unimpeachable seam attack that has been obliterated in 3 consecutive 4th innings when we should have won. None of Southee, Boult (ok he had a decent series) or Wagner could stop the rot and yet it would be ridiculous to suggest that any of them aren't good, test-class bowlers. Wags may have lost a yard or two that made his short ball attack so effective (debatable) but Boult and Southee are still pretty much Boult and Southee imo.
I tend more towards the view that despite our (totally deserved and legit) WTC win, there are still weaknesses in this team and that these weaknesses are particularly exploitable in away series and against certain players adopting certain approaches to the game. Aggressive, bullying cricket on wickets without a great deal of seam movement have always been a potential source of capitulation for us, particularly in high profile away series. I mean, the defeat in Australia didn't reveal a weakness that we then rectified by winning the WTC, it was a weakness that's always been there but which we can hide in the right circumstances or if Plan A works. In a sense this is about the deterioration of the WTC team, but there were also reasons why I sort of foresaw this happening anyway (aside from trolling and superstition).