As I noted in a previous post (For Those Condemned to Study the Past - Whenever Possible, Count!), this is known as hindsight bias, a term coined (I believe) by the social psychologist, Amos Tversk, which (according to Tvesky) is "the tendency [for historians] to take whatever facts they had observed (neglecting the many facts that they did not or could not observe) and make them fit neatly into a confident-sounding story:”
All too often, we find ourselves unable to predict what will happen; yet after the fact we explain what did happen with a great deal of confidence. This “ability” to explain that which we cannot predict, even in the absence of any additional information, represents an important, though subtle flaw in our reasoning. It leads us to believe that there is a less uncertain world than there actually is, and that we are less bright than we actually might be. For if we can explain tomorrow what we cannot predict today, without any added information except the knowledge of the actual outcome, then this outcome must have been determined in advance and we should have been able to predict it. The fact that we couldn’t is taken as an indication of our limited intelligence rather than of the uncertainty that is in the world. All too often, we feel like kicking ourselves for failing to foresee that which later appears inevitable. For all we know, the handwriting might have been on the wall all along. The question is: was the ink invisible?So, yes, I'm sure that the Clinton campaign made mistakes, but on the other side of the election, I'm willing to bet that they weren't all that obvious, even for Amie Parnes and Jonathan Allen.