The Suns were beaten 108-95 at the Barclays Center and Hornacek admits that he was disappointed with his team for failing to produce their best form against the Nets.
"We can't have these semi-efforts on nights. We had terrible effort tonight," the Phoenix coach told reporters. "This team has a bunch of All-Stars on it. This should have been a big game to get hyped up.
"Maybe we were worn out with four games in five nights. I don't know."
Phoenix will look to return to form against the Orlando Magic on Wednesday night.