Forget about March Madness. It was the madness that came in May with the NBA Playoffs that gave cable network TNT the biggest month in cable history. In a statement, the network said that it averaged 3.6 million total viewers in primetime and more than a million adults 18-34. The playoffs themselves averaged more than 5.5 million viewers, with the Chicago Bulls/Miami Heat series producing a record 10.4 million. Game 5, the channel observed, not only produced the best ratings on cable for the night but the best ratings for all of television, broadcast included.