Spalletti took charge of Juve earlier this month after the dismissal of Igor Tudor.
Marino says Spalletti has inherited a squad lacking genuine quality and he told TMW: "We're talking about a team without champions. This squad can't win. And the transfer market could have been built better.
"It's not just this summer's problem; there have been gaps for some time: I'm thinking of the attacking department. Juve are now looking to re-evaluate (Dusan) Vlahovic to find a player who can finish the game. But Dusan doesn't yet have the maturity to become a 20-25 goal player.
"There's room for improvement in every area: (Randal) Kolo Muani could have been useful. Fighting for the top four is possible, but I'm convinced that Napoli, Inter, and Milan have something extra to win."
Asked what Juve should do in January, Marino also said: "On paper, it's simple: they need a leader in each department, including up front.
"Clinging to Vlahovic's relaunch makes little sense to me: I think that for Juve, aside from the occasional argument, it's a closed chapter. January is a complicated month; signing star players isn't easy. But the Bianconeri have a significant gap compared to the other big clubs: just think of Inter, who can afford can afford to have reserves like (Ange-Yoan) Bonny and (Francesco Pio) Esposito up front."