By Michael Rosenberg The two-time gold medalist laid bare her dismay immediately after suffering a rare crash in her opening event in Beijing. BEIJING, China – Mikaela Shiffrin might go down as the best Alpine skier ever, but on Monday morning here she just went down, crashing 11 seconds and five turns into her first giant slalom run. It was so stunning that it was somehow more riveting than if she had won. The numbers say Shiffrin is dominant, and she is, but Shiffrin’s brain does not run on numbers. She is vulnerable and open about it in a way that so few all-time great athletes are. She has…