The Rossoneri landed Tonali from Brescia on an initial loan, however the option to buy and bonuses could see the deal cost as much as €35 million.
Mirabelli, who worked as director of sport for Milan from April 2017 to 2018, believes that figure is too much for the midfielder given how quick they were to sell Locatelli to Sassuolo.
“He [Tonali] is a great player,” he told Radio Sportiva. “Milan did well in signing him but he needs time to show his worth even though they paid a lot for him. Costs have to be kept in check.
“When I was at Milan he [Locatelli] wasn’t available for transfer even though he wanted playing time. I was open to loaning him out or having an option to buy him back on Milan’s terms.
“He’s one of the best midfielders in Italy, it’s a shame he was sold so quickly. He could have offered so much more.”
“Donnarumma and Calhanoglu are two key players for Milan and they have shown that over the past few months,” he added.
“It’s odd to see them with so little time remaining on their contract. The more time that passes, the greater the risk of losing them is and that makes things complicated.”