A living legend of the Italian game, the veteran striker has warned his former club not to give up one of their prized assets with Premier League heavyweights circling
Speaking ahead of a clash between his old team and the A-League All Stars in Sydney on Sunday, the 39-year-old urged the Serie A title holders to try and resist advances for all-action Chile international Vidal, who has been closely linked with Manchester United.
"Juve's value will be decided by what they can build now, the objectives they set themselves and how the transfer market pans out," Del Piero told Tuttosport.
"Obviously, I am thinking of Vidal. It's not that he is irreplaceable, but a great deal does change if he's there or not.
"If you do decide to sell, then you need to spend that money wisely. You have to buy someone just as strong, although probably a pair of players, seeing as Vidal runs for two.
"His departure would change the balance of the team, even though a midfield with (Andrea) Pirlo, (Claudio) Marchisio and (Paul) Pogba would still be very impressive.
"I also think the worth of this Juve will be given by their opponents. Last season broke records and that won't happen again. It developed that way because Juventus are strong, but also as other teams were rebuilding."
Juve embark on the 2014-15 campaign with a new face at the helm, Allegri having taken over following the sudden departure of Antonio Conte, who quit just a day into pre-season.
"I received a text message from a friend with the news, even if I had heard a little something before then ... I think the real story of this split can only be known and explained by the protagonists. The two sides of the story," Del Piero said when quizzed on his former team-mate's shock exit.
"It was a real shake-up. Usually these things happen at the end of the season, so it's decidedly more unusual to see it at the start of pre-season training."
Del Piero has witnessed Allegri, a Serie A-winning coach with AC Milan in 2010-11, working with the Juve squad first hand this week and offered the new man - an unpopular choice with many supporters - his tentative approval.
"I think Allegri has already created a good rapport with the lads. I could see them joking around between themselves, even with the President, so Allegri seems to be settled in already.
"At Juve everyone is well aware this is a very delicate moment. They are opening up a new era."
As for his own situation, Del Piero is set to play on for at least one more season, although he is yet to reveal his next destination. Whatever happens on the field, a role behind the scenes with La Vecchia Signora awaits - when the World Cup winner is ready.
"Obviously returning to Juve as a director represents an option for the future, as I still have my house in Turin and could never say no to Juve," he said.
"I am far too tied to the Bianconeri world."