The Scotland international, who scored 28 goals last season, was sold to the Cottagers for £11m in July.
McCormack has now revealed that the arrival of controversial club owner Massimo Cellino was the catalyst for him leaving Elland Road.
"When Leeds went back for pre-season training, I went in that day and was told not to train by the club because they were talking to Fulham," the 28-year-old told The Sun.
"They didn't want me getting injured with the size of the fee. It was important to the club that they didn't miss out.
"I felt it was pretty nasty in the end. It was never going to be, 'Thanks for last season, thanks for the help you gave the club'. Cellino named his price and he got it. Was I hung out to dry? In my opinion, yes."
McCormack has scored one goal in six appearances for Fulham so far this season.