For the official story to hold up, Oswald had to be hightailing it down the stairs from the Sixth Floor after the shots to make it to the Second Floor lunchroom in time for his "encounter" with Baker 90 seconds later.
Vicki Adams' insistence that she saw or heard nothing while she and Sandra Styles went down the stairs during this critical time-frame seriously undermines the official account. Since Warren Commission apologists and many conspiracy theorists postulate the Second Floor lunchroom encounter absolutely did happen, they maintain Adams and company are simply mistaken about when they went down the stairs. They understand if Vicki and Sandra were correct, Oswald wasn't on the stairs and therefore couldn't make it to the Second Floor in time for the rendezvous with Baker and Truly. And if people start going down this path, a whole lot of things start to unravel.
But Oswald running down the rear stairs is not the only part of the official story damaged by Adams' statements.