4. Adam Johnson
Johnson was a dynamic English winger. After playing for Manchester City, he moved to Sunderland where he became a key player. However, his career crashed to a halt when police arrested him. This came after he groomed a 14-year-old girl (via Mirror). It rocked the soccer world because of his profile.
He admitted that he kissed the underage girl and engaged in sexual activity. He manipulated her on Whatsapp before committing the sickening act. First, Sunderland suspended him while the investigation was ongoing. Then, they fired him for being such a disgraceful human being.