Tardelli was reflecting on Juve's 3-2 win against Galatasaray in midweek, which saw them lose their Champions League playoff 7-5 on aggregate.
He told La Stampa, "Why those five goals in Turkey? A team that's difficult to decipher, lacking consistency: just when you seem to see the light, you're back in the tunnel.
"Luciano (Spalletti, coach) had managed to revitalize his players, despite the impalpable (Jonathan) David who continues to be a foreign body for the team."
Tardelli added: "Unfortunately, in football, results count, and right now they're not positive. Now comes the match against Gasperini's Roma, which could truly prove decisive, turning the present and future of the Bianconeri club on its head."
