Mets top pitching prospect Zack Wheeler may be further away than first thought.

With the Mets hoping Wheeler can save this season as their third starter, he fell flat Friday at Triple-A Las Vegas, yielding four runs and three hits while striking out four and walking six in 4⅓ innings against Sacramento.

"I haven’t talked to (Las Vegas manager) Wally (Backman)," Mets manager Terry Collins said Saturday. "When you’re playing in Las Vegas, due to the (small) ballparks, sometimes you overthrow because you just don’t want to get hit.

"Sometimes, those guys in those parks pitch away from contact because contact means danger in those parks. The ball flies. We know one thing with Zach’s history: He doesn’t walk a lot of guys. So when I saw the six (walks) there has to be a reason for it."

"He has good enough stuff that if he pounds the zone he’ll get people out. That (six walks) is a red flag. I don’t want to see walks from those guys. I’d rather see 10 hits. That I can understand. But six walks, he’s better than that."

Overall, Wheeler is 0-1 with a 4.91 ERA this season. He has allowed 13 runs (10 earned) and 20 hits while striking out 21 and walking 12 in 18⅓ innings.