Here’s a surprise: “American Idol” beat “The Voice” last night in a head to head ratings war. “Idol” scored a 2.8 to “The Voice”‘s 2.7 in the key demo. (“Idol got a 2.5 in the demo from 8 to 9pm during the hour it shared with “The Voice.”) But more importantly, “Idol” drew 2 million more total viewers– 10.8 to 8.7 million. All the crazy publicity for “Idol” may have added to the audience. Plus the main contestants– Candice Glover and Angie Miller–were top notch last night. The big slide for “The Voice” in audience is really shocking, though. Their demo numbers are almost half of what the were a couple of weeks ago. Is the audience that fickle? Or is it just that “The Voice” competitors aren’t compelling? “The Voice” was actually in fourth place overall for the night, beaten by “Survivor,” “CSI,” “Modern Family,” and “Criminal Minds.” Success turns on a dime in Hollywood.