The Warriors achieved some great things, and they also had some luck. That doesn't take away from their achievements, every great team usually has at least some luck, but they did have a string of good luck there for a while.
Then, in the last few weeks especially, their luck started to turn a little bit. Curry picked up an injury, Draymond got suspended, Bogut got injured. Even a couple of 3's from yesterday that would normally go in for them were in and out. Just the way it is.
Teams also started to figure them out a little bit to the point where they didn't look invincible. The T'Wolves starting switching on them which worked well and other teams followed suit. Other teams starting exposing GSW's own switches and isolating Steph on defence. When Ezeli was on the court yesterday the Cavs just ran like 4 straight plays where they got the switch of Ezeli onto James on the perimeter. OKC and then the Cavs hammered them on the boards although that wasn't exactly a secret or a new tactic.
I think the term choke is overused but you could maybe apply it here I guess. 73-9, up 3-1 in the Finals, you shouldn't lose. I don't want to be too negative because the real story is LBJ and the Cavs but it should be noted for the record that Curry was awful, particularly for an MVP. His worst traits that I always suspected were there were brought to the surface. That being said he's a hell of a player and he'll be back.
I wondered near the start of the playoffs whether the Warriors had emptied the tank a little bit chasing the record. I thought they had gone too hard for it and it might end up costing them. Whether that was the deciding factor I don't know but they may look back on it in time and wonder.