Here's the truth.
We all (or most) overreacted to the win against Cleveland (whether you want to admit it or not).
We all (or most) are now overreacting to the loss against New Orleans (whether you want to admit it or not).
We've had a couple stinkers like this every single year the past few years.
In the end, nothing has changed. We'll be the same 10-12 win team we've been the past few years. And we'll lose in the playoffs, most likely in the first 2 rounds.
I've said this before, but the issue in the offseason was never that we're going to suck now. It was always that we didn't do anything really to get over the hump in the playoffs. We'll be decent but that's not good enough.
Nothing has changed.
As for why this keeps happening?
Just a guess, but maybe relying on a bevy of rookies and first year players every year isn't conducive to getting a consistent stable performance every week. Just a guess.