How zone defense lets players off the hook

Reluctantly, HOU coach Rick Adelman has had to play some zone defense in the last few games. But he makes it clear that he's not a supporter of zone:

“I never liked it. Sometimes it throws a team out of whack. I think it’s good to change up once in a while or take someone out of their comfort zone. I’ve always found, in the NBA especially, it kind of lets people off the hook as far as their responsibilities for defending. Now you’re telling them, ‘No, you’re just playing a spot.’ It lets people just stand around, instead of having responsibilities for their man and helping their teammates.”