The strategy of putting money and time and effort and resources into states like Arizona and Iowa and Georgia, or even solidly blue states like my own state of New Jersey. Resources that could have been better spent in "swing" states that we lost by razor thin margins.
That is it. That is the beginning and the end of what went wrong this election. In short, assumptions and hubris did us in.
We won the popular vote by a lot.
We only lost those "must win" states by a ridiculously small margin. A margin small enough that some really solid GOTV could have shifted things in the opposite direction.
That was the only strategy that was bad this election. And like it or not that responsibility falls firmly within the Clinton camp. Not her directly as I would assume that is not something she herself would be in charge of, but still the responsibility of her staff and the people she hired and the people she charged with one job and one job only, and that is winning the election.
Everything else, every other discussion is nothing more than small details around the margins.
We don't need a major overhaul. We don't need to discuss purity or compromise. We need to discuss the proper allocation of resources and the need to do a full court press every election in every location. That is it. That is the area that we failed on.
There's the other issue of how complacent and lazy we get in between presidential campaigns and the fact that we focus myopically on the White House at the expense of everything else, but that is for a different discussion.