He said: "The club did what it could, taking into account both technical and financial aspects.
"To me, it went well because I have a young squad with alternatives in every position.
"Milan have signed champions that no one could have imagined, but only time will tell who has done well and who hasn't.
"I remember that a year ago, everyone praised Juventus' transfer campaign. After the first few games they seemed in a position to compete with Inter, then we know how it ended.
"The debate about Diego is wide. It also regards the financial aspect and involves the club, but we are all aligned.
"It's up to the club to respond [to Diego's criticism]. I will only say that Diego is a great player and I hope he finds success in Germany, but we have more presence in the penalty area with Quagliarella. And then again, our Diego is called Del Piero."
When it was pointed out that Diego is much younger than Del Piero, Del Neri said: "What does that matter? At 35, Doni played 30 games with me at Atalanta and scored 12 goals.
"I can't assure a starting place to anyone. Del Piero is a Juventus player and it's important that he is happy. Then we'll see what happens.
"We must get a place in the Champions League in whatever way possible, because the history of Juventus requires it."