Pacific Classic: Alvarado says Knightsbridge has speed to stay

The question is like a mantra during Kentucky Derby week. How are these 3-year-olds going to get that extra sixteenth or eighth of a mile that they never have raced before? J nior Alvarado heard it before he rode Sovereignty last year at Churchill Downs, and that worked out just fine. Now he is hearing it about 5-year-old Knightsbridge , the favorite for the Grade 1, $1 million Pacific Classic…