NEW YORK >> The New York Mets said nighty-night to the Dark Knight.

Matt Harvey, once regarded as a premier pitcher who could join Tom Seaver and Dwight Gooden among the Mets’ greats, refused a minor league assignment and will be designated for assignment Saturday.

The 29-year-old right-hander lost his spot in the rotation last month after four starts, and he had a 10.50 ERA in four relief appearances.

“We’ve tried to find some other solution over a fairly long period of time,” Mets general manager Sandy Alderson said before today’s game against Colorado. “This was a long time coming. This is not someone who hasn’t pitched well recently. So I mean this is something we’ve tried to address, we’ve struggled with, we’ve wrestled with over two managerial regimes.”

After Harvey is designated, the Mets have seven days to trade him or release him. Because of Harvey’s $5,625,000 salary, a trade may be difficult to work out unless the Mets agree to send cash as part of a deal.

Harvey is 0-2 with a 7.00 ERA in four starts and four relief appearances, leaving him with a 34-37 record and 3.66 ERA in six major league seasons.

“The move to the bullpen was dramatic in itself,” Alderson said. “So I think that at this point, pragmatism, realism far outweighed other considerations.”

Selected by the Mets with the seventh overall pick in the 2010 amateur draft, Harvey made his big league debut in July 2012 and became a major sports figure in New York — both at the ballpark and at Manhattan night spots.

He started the All-Star Game at Citi Field in 2013 and was 9-5 with a 2.27 ERA when he tore an elbow ligament during a game against Detroit that Aug. 24, which led to Tommy John surgery on Oct. 22.

Harvey returned in 2015 and went 13-8 with a 2.27 ERA as the Mets reached the World Series for the first time since 2000. But he slumped to a 4-10 record with a 4.86 ERA the following year and had season-ending surgery on July 18, 2016, to correct Thoracic Outlet Syndrome.

He was 6-13 with a 6.70 ERA last season, when he was sidelined from mid-June until September because of a stress injury to the scapula bone in his right shoulder. He was suspended for three days without pay in May for skipping a game following a late night on the town.

The New York Post reported this week that Harvey was out partying in Los Angeles the night before pitching in San Diego.

“Usually I get upset if a report is unexpected,” Alderson said. “So I guess the short answer is no.”