James scored twice for Leeds in their 4-1 demolition job on Huddersfield Town in the Championship on Saturday afternoon at Elland Road.
The Wales international was too hot for the Terriers to handle as Leeds bounced back quickly from a midweek loss at Stoke City.
McCormack believes that James is a player right in form at the moment and admits he was surprised when he checked how many goals and assists the former Manchester United man has been producing.
“His numbers are right up there”, McCormack said post match on BBC Radio Leeds.
“It actually surprised me when I looked at it a couple of weeks ago about how many goals and assists he’s got in maybe the last eight, nine, ten games or something.
“He’s on fire at the minute and long may it continue.”
Leeds sent James on loan to Fulham last season and he was unable to help in the Whites’ battle against relegation from the Premier League.
Now James will be hoping to be a key man in leading Leeds right back up to the top flight.
