Something I just realised when looking at Anduin's video again. When the Jailer is on the joystick, Anduin's eyes turn blue. Who else had a colour change in his eyes? Bolvar, when fighting Sylvanas.
Do you think the Jailer decided to take control over Bolvar to make sure that he lost, because he was afraid that Bolvar would've ruined his plans if he had defeated Sylvanas?