McLeish said: "Zarate is still learning the team game and if he had gone to bigger clubs you probably wouldn't have seen him for six months.
"But we've embraced him, encouraged him, and he is popular with the squad.
"I've got to be careful I am not throwing him in every week just for the sake of the individual skills he has got because I've two experienced strikers out there.
"We knew we had a deadly weapon to come off the bench in Mauro. I said to him before the game he would be disappointed but he could still make an impact and he certainly did that."