Vernon Davis, Delanie Walker, Patrick Kerney and Aeneas Williams are among the current and former NFC West players called upon to speak at the NFL's annual Rookie Symposium next week. The NFL made the announcement Tuesday.Davis, entering his eighth season with the San Francisco 49ers, was once an immature young player prone to outbursts on the field and during practice. He has grown into a steady team leader with varied business and community interests.