David Moyes has asked Manchester United's fans to trust him over the handling of Zaha.
Sir Alex Ferguson's final signing as United boss was expected to make a big impact at Old Trafford this season.
Instead, the £15million arrival from Crystal Palace made just four appearances including the Community Shield, and has now been shipped out to Cardiff on loan.
Various theories have been put forward for Zaha's strange absence from the United fold, some of which related to his attitude.
However, after a spellbinding performance on his Bluebirds debut that inspired a victory over Norwich last weekend, those questions about his non-appearance have been raised again.
"At times you have to believe what the manager is seeing as well," Moyes said.
"There is big competition for those wide areas.
"When I came in, I had Antonio Valencia, Nani and Ashley Young. Then we had the emergence of Adnan (Januzaj). Shinji (Kagawa) can play off one of the sides.
"I have seen Wilfried training every day as well. I am privy to that."
Indeed, Zaha had been told he could go out on loan if the opportunity arose, only for injuries to delay his exit until the end of last month.
"We might have got him on loan even earlier but for the (hamstring) injury to Nani. I just wanted to see how that was," Moyes said.
"It is good for him, it is good for his development. Everybody will have a chance to see how he plays.
"The idea is he shows what he can do and comes back a better player for Manchester United."