Quin was trying to pull the play he did against Houston, expecting Curry to switch onto Mack (because Steph is the weakest defender on that team-- they ran it against Houston last time because Harden is a way ****tier defender than Bev or Ariza.
Unfortunately, two things happened-- the 1) switch didn't happen; and 2) Hayward assumed the switch was gonna happen, so he wrongfully decided to pass to Mack (who was only to be passed to, if the switch occurred).
Consequently, Draymond made the right read, and a better stop. Hayward shoulda held on, and gone for the iso. But guess what-- players make mistakes. It worked last game, didn't work this time. And while many will pin his loss on Hayward for botching this play, we gotta blame it on FTs at the end of the day. Fortunately, I can't exactly remember too many close losses thanks to FTs, so I'm not concerned.