It's a combination of a few things Oswin.
The Roosters' ball handling was terrible. Dropped balls all over the park.
The Bunnies played pretty well, their defence just letting them down a couple of times.
Their attack, in areas was similar to the Knights form of "razzle dazzle" and "anything goes" style, where the ball goes through almost every set of hands on the park, and a few sets of feet, before the try was scored.
One of their try's will go down as a contender for try of the season. It was very entertaining to watch.
Hopefully Souths can maintain the quality football and improve to bcome a contender this year.