Ferguson led Peterborough from League Two to the Championship
Peterborough captain Russell Martin says the players were to blame for manager Darren Ferguson's departure.
The club confirmed the 37-year-old, son of Manchester United boss Sir Alex, had left by mutual consent on Tuesday.
Martin told BBC Radio Cambridgeshire: "We're surprised and disappointed because the responsibility falls on us at the end of the day.
"We've let Ferguson down this season. While performances at times have been good we haven't got the results."
Martin, 23, has found himself out of favour in recent weeks.
But the right-back, who Ferguson brought in from Wycombe in 2008, was keen to pay tribute to his former boss.
He added: "He's improved everyone as a player. As a person everyone's got a lot stronger.
"But that's football, the decision has been made. We've got a massive challenge ahead of us and we can't let it affect us. The boys are despondent at the moment but we'll have to pick ourselves up."
Supporters had to wait more than 24 hours between news reports of Ferguson's departure appearing and the club confirming the situation.
Posh chief executive Bob Symns explained: "The delay has been talking through the issues, the challenges for everybody involved and making sure everyone is happy with how the departure has been managed."
Meanwhile, United have confirmed that assistant manager Kevin Russell has resigned.
"We would like to thank Kevin for his efforts for the football club," said a statement on the club's website.
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