NEW YORK -- Terry Collins spoke Wednesday afternoon of managing the innings for second-year right-hander Zack Wheeler. The New York Mets manager didn't exactly want Wheeler to make the task as easy as he did a few hours later.

Wheeler endured his worst start as a big leaguer Wednesday night, when he allowed a career-high six runs on six hits over a career-low two innings as the Mets fell to the Oakland Athletics, 8-5.

Wheeler's performance was particularly disheartening considering he was coming off his best performance with the Mets -- a three-hit shutout of the Miami Marlins last Friday in which Wheeler faced just one batter over the minimum.

But such inconsistencies are part of the maturation process for Wheeler, who is 3-8 with a 4.45 ERA this year and 10-15 with a 3.90 ERA in 33 starts since being promoted from Triple-A Las Vegas last June 18.

"He pitched so well last week," Collins said afterward. "I said to (pitching coach) Dan (Warthen) on the bench -- sometimes you do see a little bit of a letdown after an effort like last week.

"He just didn't bounce back. He didn't have it going tonight."

The Athletics squared up so easily against Wheeler -- first baseman Brandon Moss launched a two-run homer deep into the upper deck in the first inning while left fielder Yoenis Cespedes laced a three-run double down the left field line in the second -- that he suspected they had figured out his signs.

"They were on to my signs in the second -- it's my fault for not catching on to it sooner," Wheeler said. "When somebody turns on a 96 mph fastball, they probably knew it was coming."

Collins didn't address the signs issue but acknowledged Wheeler's struggles Wednesday were unprecedented at the big league level.

"I have never seen him get hit that hard -- ever," Collins said. "I've seen him give up home runs, but never get hit hard like that."