Kevin-Prince Boateng, a former AC Milan midfielder, already had serious physical issues at Eintracht Frankfurt.
"He knew that he could no longer manage the workload in two tough competitions - and that he would no longer be able to meet his own demands," said Eintracht President Peter Fischer in an interview with "Bild" about the midfielder's departure in summer 2018.
Boateng is now back under contract with his hometown club Hertha BSC. Since the start of the season, the 34-year-old has only played 14 competitive games because of his complaints.
Most of these were brief assignments. Boateng is expected to let his contract expire in the summer and retire.
Hertha fans rarely see him in action anymore: Kevin-Prince Boateng hardly plays a sporting role.
The former AC Milan midfielder Kevin-Prince Boateng left Serie B club Monza on a free transfer to return to Bundesliga club Hertha Berlin.