Because the Burnley forward was in an off side position earlier in the move when the ball was played forward. He became offside when he touched the ball after the defender slipped and the lineman immediately flagged. Correct decision and correct timing in pre VAR days. But I don't understand why the lineman flagged immediately. I thought they were now supposed to delay flagging so play could develop and then VAR would correct an error if a goal was scored.
The lineman flagging immediately happened several times against City yesterday. I don't know why?