SYDNEY — David Leckie has been tapped CEO of Australia’s second-ranked Seven Network, 15 months after being dumped from the top job at Kerry Packer’s market leader Channel Nine.The appointment makes Leckie the third Nine exec in the past three months lured to Seven by its chairman Kerry Stokes. In January John Stephens shocked the industry by defecting to Seven after a decade of programming Nine to No. 1. Then Nine’s long-serving news topper Peter Meakin also defected. Both aided Stokes’ bid to lure Leckie to the net’s top job. Former CEO Maureen Plavsic will retain her board position and have responsibility for maximising efficiencies and synergies between the network and its magazine division, Pacific Publications.