THE ESSENCE: A stable year followed an up-and-down 2004 that included the loss of Pier One and the agency's big Alltel win. It didn't lose-or win-any big accounts and hung onto the U.S. Navy. Chevrolet handed some assignments to Deutsch, but Campbell-Ewald's position on the account is seen as secure. The agency increasingly pushed into nontraditional work, whether it was redesign of Alltel stores or an online game for the Navy. This year promises to be a challenging one with bedrock client General Motors Corp. The troubled automaker is squeezing agencies for a return on their investment, with a lot riding on the launch of the redone Chevy Silverado.