Edit: was Martin, not Lowry.
I think Pop had the right idea. Green was playing Martin out near the half-court stripe and was virtually begging to be drove right around, which would have probably ended up in an even-more-open look for another Rocket after the Spurs rotated to help. Spacing Martin was smart...Green just retreated a step too far back. He was hanging behind the three-point line instead of staying outside at the top of the arc. If he stands outside the stripe, I doubt Martin puts up that 30-footer...and even though he made it, it's still hard to call that a quality shot. I'll take a rushed, semi-contested long-three from a moderate shooter over an open shot every day of the week...if he makes it, you just tip your hat and get back on D.
After the play and ensuing timeout, it looked like Pop was telling Green the same thing...space him, but still contest the three-point line. I wouldn't blame Green for being frustrated though....he tried to take his coach's advice, and got burned for it.