Traditional TV’s advertising model is experiencing significant shifts, and that trend was made no more clear than during Turner Broadcasting’s upfront presentation this year. Turner is hoping to drive more value for its US advertisers by pitching cross-screen “omnichannel” advertising opportunities with premium content and highly engaged audiences. “We’re no longer in the Nielsen, day part, CPM game,” said Turner Networks CEO and chairman, John Martin, speaking at the recent MoffettNathanson Media and Communications Summit in New York. “We’re in the fan-engagement business.” Turner and the other TV networks are feeling the effects of declining ratings and increased pressure from advertisers. While content consumption is on the rise across age demographics, viewers aged 18-49 are watching less linear TV each…