PHOENIX -- Zack Wheeler has been shut down for two weeks and he might not pitch again this season.
On Wednesday, the Mets right-hander was diagnosed with a mild flexor strain in his right arm by Dr. James Andrews. An MRI showed no damage to Wheeler's ligament.
"We started out the year very confident that sometime in July he would be back," Mets manager Terry Collins said. "Then as the summer proceeded on and he never felt comfortable, especially in the last month when it seemed that every time he got on the mound, all of sudden there was discomfort. We had to realize that this may not be what we thought was going to happen."
Mets assistant general manager John Ricco acknowledged that the "clock is certainly ticking" on Wheeler's season, but stopped short of saying the pitcher is done for the year. What's certain is that Wheeler will receive an injection and the club will re-evaluate in a couple of weeks.
"The good news is that the ligament was intact and no problems there," Ricco said. "The muscle strain was the cause of some of the elbow soreness."
Wheeler underwent Tommy John surgery on March 25, 2015, to reconstruct a torn UCL in his right elbow, as well as repair the flexor pronator tendon in the same elbow. The Mets hoped that the 26-year-old would be able to rejoin their rotation in June, but setbacks pushed the timetable back to early September.
Now, his season is in doubt.
"We are very disappointed," Collins said. "I feel bad for Zack. I know he certainly wanted to pitch and was looking forward to pitching, but nobody knows how he feels any better than he does. I just hope with the rest and recuperation, certainly he can come back in the future and be effective."
Wheeler last pitched for New York on Sept. 25, 2014. In 49 career starts, he is 18-16 with a 3.50 ERA.
Worth noting
• Second baseman Neil Walker was not in the starting lineup Wednesday for the second consecutive game because of lingering back stiffness. He is considered day to day. Walker's wife, Niki, is expected to give birth to the couple's first child anytime. She was due Tuesday.
• Yoenis Céspedes, who has been on the disabled list since Aug. 4 with a strained right quad, remains on track to join the big league club for the weekend series in San Francisco. He's 0-for-6 with one RBI in his first two rehab starts for Class A Advanced St. Lucie. He was set to play left field Wednesday.
• Asdrúbal Cabrera, who has been on the disabled list since Aug. 1 with a strained left patella tendon, went 1-for-3 with a double in four innings at shortstop for St. Lucie on Tuesday and is expected to play shortstop again Wednesday. Cabrera, who is eligible to be activated from the DL, is also expected to join the team in San Francisco.
• Justin Ruggiano, who has been on the disabled list since Aug. 2 with a mild left hamstring strain, went 2-for-3 with walk for Triple-A Las Vegas on Tuesday.