Gardner netted his fourth goal of the season in Tuesday's Carling Cup win against MK Dons to maintain his fine start to the campaign.
McLeish is happy with Gardner's goalscoring return so far this term and he believes he can have a similar impact to Lee Bowyer last season.
"I'm delighted for Craig," McLeish told the club's official website.
"Last year Lee Bowyer scored six in the first half of the season which was instrumental in our very good run and Craig has come in and shown that he can score goals.
"A goalscoring midfielder is very rare and it's hard to find them.
"Frank Lampard is probably the stand-out individual in his position in the Premier League over the past few years, but it's good to see Craig getting amongst the goals.
"Not only has he got a very strong shot but he gets on the end of things in the box as well.
"I've been pleased with Craig's return and he's been doing it on the training ground every day."