Leeds Utd's injury time equaliser was interesting as a Cardiff defender was almost completely off the pitch apart from his hands which I assume ruled out any question of offside. However my question is if the Cardiff player had been completely off the pitch, would that have brought offside into play? I am fairly sure the Leeds Utd goal scorer would have been offside if the aforementioned defender was sat on his arse further up the field.
No, as a defender that leaves the pitch is deemed to be on the pitch for the purposes of offside.