Bayer Leverkusen playmaker Michael Ballack has failed to deliver in his 20 months at the Bundesliga club after joining in 2010 from Chelsea, club CEO Wolfgang Holzhauser said on Friday.
The former Germany captain, who lost his spot in the national team last year after missing the 2010 World Cup through injury, has not always done his part for the good of the team, Holzhauser told Cologne's Express newspaper.
"The time has come for all of us to admit that our thoughts of 20 months ago have not been realised," Holzhauser said.
Ballack returned to Leverkusen, with whom he lost in the 2002 Champions League final, with great expectations but failed to hold on to a regular spot due to a string of injuries.
Last season's Bundesliga runners-up have qualified, however, for the Champions League round of 16 where they face Barcelona, with Ballack contributing a goal and two assists in the six group stage matches.
"From Michael Ballack we expected more on a sporting level and he surely expected more from himself," said Holzhauser.
"He should think about whether his behaviour is for the good of the club. [Sports Director] Rudi Voller and myself have talked to him this week but unfortunately without success," Holzhauser said.
The 35-year-old was taken off on the hour in their 3-2 win against Mainz 05 last week, shaking his head and refusing to acknowledge coach Robin Dutt.
Ballack has said the current campaign would most likely be his last for Leverkusen but he intended to continue his career for a couple of years longer.