NSW isn't locked down and we managed to sit at around 15 cases per day for a good while without it spiralling out of control and have dragged it right down to 0

NSW isn't locked down and we managed to sit at around 15 cases per day for a good while without it spiralling out of control and have dragged it right down to 0's some days and close to it on others. So if you assume that Victoria can contact trace almost as well as NSW, I think its fair to say it's worked because they've got to a number where contact tracing is effective.