Despite the work of coach Luciano Spalletti since his arrival, Tacchinardi says he's been held back by the lack of quality in the players.
He told La Gazzetta dello Sport: "We lack ambition. This team is timid: if they lose, they struggle; they lack character.
"I would tell them: 'Mister, they lack character'. They haven't signed a single player with charisma on the market. That's what is missing."
On Spalletti, Tacchinardi continued: "Yes, he's the right man, but he can't do it alone. He needs two or three strong players, like at Napoli. He's a strong coach.
"I had dinner with him before he arrived in Turin; (Ciro) Ferrara and (Alessandro) Del Piero were with us. At the end of that dinner, I said to myself, 'I really hope he comes to Juve.'
"But Spalletti needs top-notch players, otherwise he can't work miracles."