SAN DIEGO — As a 12-year-old living in South London, a tall-beyond-her-age girl romping around a neighborhood field caught the eye of the manager for the Chelsea Ladies program. Unlike many others in Chelsea’s senior division, Casey Stoney did not own a driver’s license. What she possessed, though, was an intriguing cocktail of skill, confidence and unimpeachable work ethic. That revealed itself at 10, when the only girl in an all-boys league fought through the ribbing and derision to become team MVP. “You’re not legally supposed to play (seniors) until you’re 14, so we used to fake my date of…