EAST RUTHERFORD, N.J. ? A day after signing his first long-term contract as an NBA head coach, Lawrence Frank wasn’t in a mood to celebrate.

Between the joy of extending his childhood dream and the news conference to announce it on Thursday, Frank had to watch his New Jersey Nets play a horrid game in a 100-77 season-opening loss to Shaquille O’Neal and the Miami Heat.

It was the franchise’s worst opening-night loss since joining the NBA in 1976.

Talk about letdowns just hours after signing a 4-year, $10 million contract extension.

“You can search for reasons and I take responsibility, but we just played out of character,” Frank said. “We didn’t have much of a presence out there.”

That may not be too surprising this season.

Frank has re-signed to coach a team that has been transformed from the leading contender in the Eastern Conference to one that will be lucky to make the playoffs with Kenyon Martin gone and Jason Kidd sidelined indefinitely with a knee injury.

There were three new starters — guards Jacque Vaughn and Ron Mercer and forward Eric Williams — in the opening night lineup, and six new players on the 12-man active roster on Wednesday night.

“I think that there is nobody that knows more about the game than Lawrence does, nobody prepares better and no one has a passion for this game any more than Lawrence,” Nets president Rod Thorn said.

For the most part, Frank negotiated his own contract, saving a 4 percent agent’s fee. He spoke with fellow NBA coaches for advice and got some legal help in fashioning the deal.