One area I'd defend McGhee would be his development of McCormack, Quinn and Clarkson, which led to sizeable income. During his tenure we also knocked back an offer in excess of £700k for Reynolds iirc. So he has a pedigree at FP for developing our young players.
Regarding McGhees departure however, seemingly walking away to save us cash. Did his challenging wage not stem from a rise post Hearts flirtation?