Let me rephrase: you are extrapolating the wrong thing when you say the "liberals drastically overplayed their hand" and then use this election as evidence.

Obama almost certainly would have annihilated Trump (his support in rural swing states is much stronger than Hillary's), and he's more liberal than Hillary. For all we know, Bernie could have done decently. Hillary's downfall is that she's seen as an out-of-touch corrupt establishment politician, which Trump (and Obama) were not.