Zigic impressed in last night's Carling Cup win over MK Dons.
"It is a completely different game in England to the one he plays on the continent,'' McLeish said.
"He is more used to playing the ball on the ground.
"We know he is 6ft 8in, and players will think that if you launch high balls at him all day ... but that is not the biggest part of his game, although he should be able to get us into areas high up the pitch where we can keep the ball alive and be on to the second balls.
"He is a decent footballer but he is having to find time to adjust to things, the speed of the game.
"On the continent they pass the ball and wait for the right moment before playing it to the strikers. In England, you tend to get it to the strikers as quickly as possible.''