With the back end of the Mets rotation struggling through the first two weeks of the season, calls for top pitching prospect Zack Wheeler are getting louder. Even Terry Collins said he might have to think about asking for some of the young, quality reinforcements the franchise has stockpiled in the minors if the struggles continue.

On his weekly radio spot on WFAN, Collins was asked if the pitching beyond Jon Niese and Matt Harvey continued to struggle would there be a chance the club could call up Wheeler soon. “If this continues, we’ve gotta start visiting that pretty soon,” Collins told WFAN host Mike Francesa.

While Sandy Alderson did not rule out Wheeler’s promotion, the GM said the decision would not be made because of the struggles of Dillon Gee, Jeremy Hefner and Aaron Laffey.

“It was always a case that it would be Zack’s sufficiency and the major-league team’s need,” Alderson said. “If those two things merge, the need and the performance converge, then it is a possibility.

“That could happen sooner or it could happen later,” Alderson said.

At the moment, performance has not met the need, no matter how bad the back end of the Mets rotation has been. While Jon Niese and Matt Harvey have combined to give up nine earned runs through 39.2 innings and the Mets are 6-0 in their starts, Gee, Hefner and Laffey have struggled. The three have given up 24 earned runs in 31.1 innings over seven starts.