On the short list of unambiguously beloved sports heroes here in the Valley, along with Larry Fitzgerald, Shane Doan, Luis Gonzalez and a few others, there’s only one – so far – that has had a big-time Hollywood biopic made about him. Quarterback Kurt Warner, who in 2009 led the Arizona Cardinals to their only Super Bowl to date, is the title character of American Underdog, last year’s saga of the struggles and triumphs of Warner...