The trio were all picked up by Melbourne in the 2017 draft, and have extended their deals through until the end of the 2020 season.
Fritsch has been a revelation for Melbourne after being drafted out of the club’s VFL associate Casey with pick 31, averaging 16 disposals and booting nine goals.
The high-flyer’s recent move to the wing has produced his best form for the season, where he has averaged 22.3 disposals over the past three weeks.
“Bayley, as a mature-age recruit, has been able to come into our side and play a role immediately in the forward line and on the wing,” Mahoney told AFL.com.au.
Spargo, who was taken with pick 29, has injected the Demons with speed, energy and class inside 50, after coming into the side in round six against the Bombers.
“After a late start to pre-season due to shoulder rehab, Charlie has been able to contribute at AFL level as a forward,” Mahoney said.
“He has shown the pressure and football smarts that our recruiters saw in him when he was selected with our first pick in the draft.”
Petty, their pick 37, is yet to debut for Melbourne but has shown strong form in the VFL. The 197cm key defender figures to be an important part of their future.
“Harrison is developing well at Casey as a key defender and shows all the signs of a potential AFL defender in the future,” Mahoney said.