The former Brighton man was central to Cardiff's emphatic 4-0 win over Burnley that took them top of the Championship, scoring one and tormenting Burnley's defence all game. And Mackay is confident the winger will continue to improve.
"He has such potential and there is so much more to come," Mackay told the South Wales Echo.
"I tried to sign him at Watford and as we have the same recruitment guys here - Iain Moody and Mark Stow - we tried to tempt him out of Brighton in January, but it wasn't to be at that stage.
"Craig has bags of personality. He has huge talent and that's the starting base. He desperately wants to learn and has such potential.
"Training has stepped up and we push the players relentlessly and Craig has benefited from that."