Frattesi grew up as part of the Giallorossi youth academy and is a lifelong fan of the club, so when the opportunity arose to make a return, he jumped at the chance.
However, the two clubs could not agree financial terms and the deal collapsed, with Frattesi refusing to consider other alternatives such as the Premier League.
He later admitted that this disappointment had badly affected his form and he was not ‘professional’ enough in the circumstances.
“I think Sassuolo should be seen as a launchpad towards a big club and Frattesi has everything it takes to make that leap,” Carnevali told the Corriere dello Sport newspaper.
“We need to find an agreement that will suit all three parties. We will find the best solution and try to make the player happy.”
There had been suggestions Sassuolo could accept Roma players like Edoardo Bove and Cristian Volpato as part of an exchange to lower the asking price for Frattesi.
“We had already been following them, both in January and before. Roma have many talented young players and sending them to us with a cut of any future transfer fee could be a good opportunity. They’d have the chance to show what they can do at Sassuolo, which was already the case for Lorenzo Pellegrini and Matteo Politano in the past.”
The two clubs will have the opportunity to discuss the situation further when they go head-to-head at the Stadio Olimpico on Sunday at 17.00 GMT.