It's not just the good job the Spurs did on Zach, but the beautifully executed backside help to deny the high-low with Gasol. That's where is gets so hard to guard Memphis. I was watching Manu and Green do a really good job of making sure that Marc Gasol saw them ready to help backside so that he was less willing to try the high-low when we were fronting Zach.
I've never seen the Spurs hit that weakside help so consistently with no mistakes. They shut down every single high-low opportunity that the Grizzlies had.
When the Spurs lose...it makes Baby Jesus cry