The summer signing scored a late double to give the Black Cats a 2-1 win over Queens Park Rangers at Loftus Road in the third round of the EFL Cup after Sandro had opened the scoring for the home side on the hour-mark.
McNair was signed by Moyes from Manchester United mainly as a defender but the manager of the Wearside club suggests there is much more off an attacking side to the 21-year-old's game as most people think.
"There is some misconception with his position. He is an attacking midfielder, he started as a boy as a number 10," said Moyes.
"He is very much an attacking midfielder. We have seen in training he is a good finisher.
"I believe he is better moving up the pitch and tonight was good for him. I think he will go on to be a really good buy for us but he needs a bit of developing."
McNair drew Sunderland level in the 70th minute when playing a one-two with Duncan Watmore and slotting beyond R's keeper Matt Ingram from just outside the six-yard box before winning it for the Black Cats 10 minutes later when knocking in a kind rebound from Didier Ndong's fierce effort.
The goals were McNair's first for Sunderland since arriving in early August and test at senior level having played 27 times for United without finding the back of the net.