Mets general manager Sandy Alderson said Wheeler has a complete tear, all but guaranteeing that the 24-year-old right-hander will need elbow-replacement surgery and miss the 2015 season.
"It's a blow, but at the same time we knew there would be a lot of uncertainty surrounding Zack and his elbow over the course of the season," Alderson said during a telephone conference call. "We're obviously not happy he won't be with us."
Wheeler had MRIs of his elbow in late September, January and Saturday, and Alderson said the first two did not show any ligament damage. The team did not restrict Wheeler's throwing program during the first three weeks of spring training, even though there was concern about his elbow.
"We had been forewarned by the doctors that his elbow was a concern and was going to have to be managed over the course of this season," Alderson said. "It wasn't clear that the ligament was involved at that time, but we understood that we were going to have to manage his medical condition over the course of this season. When he complained of the elbow pain, it wasn't a surprise to us. What prompted the MRI on Saturday was, Zack had complained about the elbow in the past, but the area of pain had increased in size."
Wheeler had his latest MRI on Saturday in Port St. Lucie. The scan was reviewed Monday at the Hospital for Special Surgery in New York and he was with a torn ulnar collateral ligament. The Mets said Wheeler planned to travel Monday or Tuesday to New York to confirm the diagnosis and discuss with team medical director Dr. David Altchek on how to proceed.
The announcement came one day after the Mets said Josh Edgin, the team's most-established left-handed reliever, will have elbow-ligament replacement surgery this week. The only other left-handed relievers in camp are Sean Gilmartin and three pitchers with minor league contracts — Scott Rice, Dario Alvarez and Jack Leathersich.
Wheeler's injury could end New York's thoughts of trading Dillon Gee for a shortstop or offensive help. Harvey now heads a rotation that includes NL Rookie of the Year Jacob deGrom, Jonathon Niese, Bartolo Colon and Gee.
Alderson said it was too early to say whether Gee would reclaim a starting spot. Gee was the Mets' opening-day starter last year but primarily had been working out of the bullpen this spring training. Gee is scheduled to start Thursday against Houston.
"We're still digesting the injury to Zack and really have not started to address that issue," Alderson said. "That's something we will look at over the next two, three days."
Wheeler was selected by San Francisco with the sixth overall pick in the 2009 amateur draft and was traded to New York two years later in the deal that brought outfielder Carlos Beltran to the Giants. He has gone 18-16 since his big league debut in June 2013, exciting the Mets with a fastball that averaged 96 mph last season.
Wheeler made his only spring training appearance March 9, allowing six runs, two hits, two walks and two hit batters in 1 2-3 innings against Miami. He pitched a perfect first, then got in trouble in the second.
Wheeler is among the prized young pitchers the Mets have been trying to rebuild around as they try to end a streak of six straight losing seasons, one shy of the team record.
Harvey, 25, established himself as a big league All-Star before being diagnosed with a torn elbow ligament in August 2013, an injury that caused him to miss last season.
Noah Syndergaard, a 22-year-old right-hander, could make his big league debut this year. He was drafted by Toronto with the 38th overall pick and acquired after the 2012 season in the trade that sent NL Cy Young Award winner R.A. Dickey to the Blue Jays.