"People tend to forget Ishmael is only 21," the Hawthorns manager told the WBA website. "He is basically a young boy.
"I believe he has got the attributes to be a big player in years to come. But he has got to plough his own furrow now, get on with it and try and make his name in the game.
"He has been given an opportunity to score goals in the Premier League and I am sure he will do that."
When asked if Miller had struggled for goals this term because he is facing a higher calibre of defender, Mowbray replied: "I am not sure the defenders are the ones who have been stopping him.
"The keepers have stopped him a few times.
"He has also hit side-nettings and got it just past the post a few times.
"But I think the point that Premier League defenders force him down the right side is fair.
"That is why we work on his right foot every day, because the better defenders will show him one way.
"He has got to get to the point where he doesn't mind which way they show him and he is just as clinical on both sides.
"He is working hard on that.
"At 21, Ish has a lot of time to develop that right foot so it becomes as clinical as his left."