The duo impressed in Sunday`s goalless draw at home to Liverpool, although neither could find a way past inspired Reds goalkeeper Pepe Reina.
McLeish said: "You are now seeing the development of Gardner because he has not played regularly in the Premier League in all his time at Aston Villa before he came here.
"It can be tough on a player physical-wise.
"James McFadden also played his first full season in England last season. In the previous seasons, he was injured when he came here when we were in the Premier League and then in the Championship.
"With Everton over three or four years, he never played a full season.
"These guys will benefit from being involved."
Source: PA
Source: PA