Garrone's row with Cassano eventually saw the striker offloaded to Milan last week.
"I always called Cassano a prima donna and that is how he had to be treated, which included closing an eye every now and then when faced with some of his 'moments.'
"We did it because we believed in him and knew how important Antonio was on the field and for the fans. We will miss him," Garrone told the official club website.
"However, there are rules that need to be respected and limits we must stand by. A team is made up of 35 people and is dealt with seven days a week to keep the balance. If the side becomes unbalanced, that risks compromising the team spirit and without that you won't get anywhere."