The Serbia international has taken time to adapt to the Barclays Premier League since his £6million summer move from Valencia, but followed up his strike against Manchester City and winner at West Ham with the only goal against Tony Pulis' side on Saturday afternoon.
McLeish said: "Ziggy has become a fixture in the team as he's become more aggressive.
"We know he's capable of finishing. If we get that type of delivery to him in the box, there's not a lot of defenders who can live with a guy that size."
He added: "When I saw the goal again, it was amazing to see him towering over John Carew, who is a giant himself.
"That is what the big fella is capable of. He was more aggressive in the second half than he was in the first, when I thought Stoke bullied us a little bit.
"But in the second we were much more enterprising."
McLeish was full of praise for his players in reviving their fortunes in the league and also clinching a place in the Carling Cup final against Arsenal in two weeks' time.
He said: "I have to credit the players and squad for their reaction to being under a lot of pressure in the last few weeks.
"We were flirting with relegation and there's still nobody safe yet. We also had a difficult semi-final and we've had a marvellous win.
"You have to credit these players for their mental toughness because a lot of people would have crumbled under that pressure."
Source: PA
Source: PA