Ex-Rangers manager Michael Beale has been forced into explaining why he shunned a substituted Sunderland player’s handshake in the club’s most recent defeat. The English manager, 43, is now in charge of the Black Cats and has had a bumpy start to his tenure at the Stadium of Light. After a 2-1 defeat to Birmingham left the club 10th in the Championship, the pressure has intensified with many fans already calling for Beale’s head. But if Michael Beale wanted any respite at all, a clip of the ex-Rangers assistant shunning young Northern Irish defender Trai Hume has added insult to injury. Michae…