The word ‘circus’ refers to the ‘World Series Cricket’ staged by Kerry Packer.
Kerry Packer saw the money-making potential of cricket as a televised sport. After that cricket became marketable game, which could generate huge revenues. To make cricket more interesting Packer introduced coloured dress for the players, protective helmets, field restrictions, cricket playing under light, etc.
The modern day T-20 or 20-20 format was not suggested by Kerry Packer.