Patosi joined City at the beginning of 2017/18 from Belgian club Lokeren to much fan-fare, notably being handed the coveted number 10 jersey in the Mother City.
Expectations were high the Bafana Bafana international could fill the void left by ex-PSL Footballer of the Season Lebogang Manyama's departure to Turkish side Konyaspor.
However, the 25-year-old ran foul of City's management for his off-field antics, which resulted in him picking up weight and underperforming for the coastal outfit.
Nevertheless, he still managed six goals in 25 games in all competitions, reminding many of his talent when he curled in a superb strike from outside the box against Orlando Pirates in the penultimate game of the season.
McCarthy is determined to get the most out of Patosi.
"I spoke to his mum and his mum gave me permission to beat his ass up, so that's my wildcard, because obviously I can't fight and beat other people's kids," said McCarthy.
"But the mum is the most important person and she's giving me direct permission if he misbehaves that I must put him over my lap and [use the] belt in the old-school style, and that'll work."
McCarthy, who struggled with his weight in his final playing days, says Patosi is currently free to do as he wishes but will have to toe the line when pre-season training starts on June 25.
"It's holidays, there's no training, there's no nothing. He's a free man to do what he wants to," he adds.
"But come the 25th of June then he's back in my care and I've got the belt.
"Na, I think Patosi ... I think he has learnt his lesson. I think you go through certain stages, phases of your life.
"If you want to be the best athlete, [give] the best performance that you [can], I think it requires some discipline. I think he's been disciplined this season. Whenever he misbehaves he gets a fine.
"It hurts, it hurts and then you grow up and you say 'is it worth it really?' Because you are depriving South Africa from having one of the best players in a number 10 position that we have seen for a long time.
"Do you want to continue to misbehave and let the greater opportunity pass you by? Aay, he'll come right, he'll come right."