Roman Weidenfeller has criticised his Borussia Dortmund teammates, telling kicker "too many individual interests" prevented the club from succeeding this season.
Weidenfeller, 37, is set to retire this summer and take over a new role at the club, which he joined in 2002.
And going into his final Revierderby against Schalke, the reserve goalkeeper said Dortmund have not been a team this season.
"Nobody constantly played at his highest level," Weidenfeller said. "To be honest, I had the impression that there were too many individual interests and not the unconditional will to carry out the collective plan."
Dortmund started well under head coach Peter Bosz, taking 19 points from their first seven games, but failed to win their next eight, leading to Bosz's sacking and the appointment of Peter Stoger.
Despite losing only to Bayern in the Bundesliga, Stoger has been under pressure from the media and supporters since signing a deal until the end of the season in December.
It appears unlikely that Stoger will stay beyond the summer, and CEO Hans-Joachim Watzke has also announced there will be several changes in the squad once again.
"At no point this season, the squad was able to work with full focus. There were too many things to discuss and come to terms with in the dressing room," Weidenfeller said. "And this cost us a lot of crucial time.
"We must be critical of ourselves, question whether we've given it our all for squad and club all the time.
"Maybe we are talking about a problem of an entire generation and about the mistaken belief that sometimes [giving] 50 percent is enough. But the reasons for that certainly are complex."
The goalkeeper's comments follow those made by Nuri Sahin, who said after a 3-0 victory against Stuttgart on Sunday that players must accept blame for a disappointing season.
Weidenfeller, a 2014 World Cup winner with Germany, told Sky earlier this week that he will stay at Dortmund beyond the end of his career, although he could not say in which position.