I really think it's just lack of concentration. 3x I saw good things happen for them, they could have put the hammer down, and instead they just relaxed and lost concentration.
For instance, the guy who stepped on the line on the inbounds play late. We get the ball, do nothing, and settle for a bad 3. That kind of thing happened 3x in the last 7 minutes.
Basically losing concentration on a possession is just asking for it.
But I'm happy they won and settled in on defense in the OT.
This will help with their confidence.
A little lucky too on Tyrese's shot.