Former AC Milan great Paolo Maldini fears the ailing Serie A giants' woes could last long-term unless there is major restructuring and investment in the club.
Milan currently sit 12th in Serie A, 40 points behind leaders Juventus, and with 10 games remaining look out of contention for one of the two Europa League qualifying sports.
The seven-time European champions, like city rivals Inter this season, could miss out on Europe altogether next season.
Maldini, who won five Champions League trophies and seven Serie A titles as captain of the Rossoneri, finds it hard to accept.
And he believes Milan's prospects won't improve unless the club establishes a longer-term strategy that will allow them to compete with Juventus and, further afield, Bayern Munich and Real Madrid.
"I feel a mixture of anger and disappointment," Maldini, who retired from Milan in 2009, told La Gazzetta dello Sport on Tuesday.
"Not so much for the results, because we've finished 10th or 11th before, but more for the fact that everything we worked hard to build over 10 years is disappearing."
Maldini, 45, believes a 2012 summer exodus of players, including the sale of Zlatan Ibrahimovic and Thiago Silva to Paris Saint Germain, was the start of the club's slide to mediocrity.
He also hit out at the leadership of club CEO Adriano Galliani, who is credited with orchestrating the recruitment of some of the club's biggest stars over the best part of 30, success-laden years.
"Some might think I'm biting the hands that fed me, but it's not the case. I'm part of the fabric of this club and I have two kids who play in the youth sector," added Maldini.
"But Milan can no longer compete with the likes of Juventus, and are no longer among the top 10 in Europe.
"Juventus have understood what it takes and restructured by establishing a solid group of Italians who know how to achieve success.
"In 2007, when we won the Champions League, I told Galliani I don't think we were the best side in Europe.
"I understood then that without major investment we would start to slide. That was the first step, but the sale of Ibrahimovic and Thiago Silva was a blow.
"Galliani is a great leader, but he's unable to understand the players. He runs things by himself, and that's no longer possible.
"Before, we had a strong group of players that held sway over the dressing room. And, as well as Galliani there was a synergy of people with the right knowledge.
"With the departure of so many players who had that winning mentality, that has collapsed.
"I don't think the fans just want to see Milan winning. They want to see a long-term project."
Milan in January hired Clarence Seedorf to steer the club out of the mire after sacking Massimiliano Allegri.
But Maldini believes Seedorf, who spent 10 golden years at the club before being part of the 2012 summer exodus, has been handed a poisoned chalice.
In 1997 Milan finished 11th under Oscar Tabarez and, after bringing back Fabio Capello, improved to 10th in 1998, leading to the latter's sacking.
When they brought Alberto Zaccheroni on board, Milan reclaimed the title in 1999.
Asked if Seedorf could orchestrate a similar turnaround, Malini was dismissive.
"Milan are light years away from that. To rebuild the squad it's going to take a lot of investment.
"This season, the results weren't going well, but I didn't believe bringing in a new coach would help matters much.
"He (Seedorf) has great courage and character, but even a coach like (Pep) Guardiola (of Bayern Munich) would not have been enough."