I get that when you prepare for a team like Dallas you can decide to leave Kleber open but in a game when he hits 3-4 of them in a row, playing at home and evidently getting hot you should adjust and start contesting him.
It seems like Quin is unable to get that it's a different kind of moneyball during the regular season over 82 games and different one in the series. Of course Kleber won't have another game like that but just losing that one changes the momentum and gives them confidence.
The same kind of analytical approach seems to be our problem in "whole game vs crunch time" situations. We have very efficient shots chart over the course of the whole game but we seem unable to create efficient shots in crunch time. And yes over the course of a game you can beat someone shooting threes against twos but when it comes to couple of possessions efficient midrange can be better weapon. And every shot you hit is a huge momentum boost.
I think this plays in to it, Quin like to play the percentages. I also can't imagine Quin coaching the players to not rotate or contest or communicate. The players hold a lot of blame with the open shots as well.