Brazilian insists players are not to blame for recent form
The Brazilian believes that coach Luigi Del Neri and sporting director Giuseppe Marotta need to take more responsibility for the side's current league position.
"The problem has nothing to do with the players, but with those who are around them," the playmaker was reported as saying to Sportal.
"I saw the match against Palermo and my ex team-mates did not seem to be at the top of their game.
"There are a lot of good players in the squad, but they need to be managed better. Whoever decides doesn't know a lot about football.
"This Juventus side is not worthy to enter into the Champions League. I hope that they can pick themselves up, but it will not be easy because the side are in difficulty."
Diego played for the Old Lady for one season before being sold to the German side.
The playmaker has risen 24 places in the latest edition of the Castrol Rankings and is now rated as the 156th best player currently plying his trade in one of the top five leagues in Europe.