Patterson was with the Jets for Friday's pregame meal and walkthrough before vanishing prior to kickoff. That prompted Idzik to call the player's agent, Drew Rosenhaus, who confirmed that Patterson was safe and free from any legal trouble.
Rosenhaus later informed the Jets that Patterson planned to return to the team's facility on Sunday, per NFL Media Insider Ian Rapoport.
"Once we learned that Dimitri was OK ... we notified him that his absence was unexcused and will be handled accordingly," said Idzik, who called the scenario "very unusual" and "baffling."
Rex Ryan told reporters that the cornerback was frustrated by calf and leg injuries, but the coach saw no evidence that Patterson was unhappy or dissatisfied.
"I'd like to talk to him so that we can figure out what's behind it," Idzik said. "What's going through his mind to take such a drastic step?"
UPDATE: Idzik and Ryan met with Patterson on Sunday night, according to the team. According to Rosenhaus, Patterson was dealing with a personal issue.