By Daniel Kline The fast-food giant has used its signature sandwich as a way to get attention for its menu. Burger King has fallen way behind in the fast-food wars. It’s not just trying to catch perennial market leader McDonald’s (MCD) – Get McDonald’s Corporation Report, it has also fallen behind Wendy’s (WEN) – Get Wendy’s Company (The) Report. That’s a humiliating fall from grace for the Restaurant Brands International (QSR) – Get Restaurant Brands International Inc. Report brand that was once clearly the Pepsi to McDonald’s Coke. The chain hasn’t fully lost its relevance but it has fallen …