By Michael Rosenberg It’s hard not to make the comparison between the two athletes. But after many got the gymnast’s story wrong last summer, let’s not make the same mistakes as the skier’s Olympic campaign continues. BEIJING — Mikaela Shiffrin is struggling on the mountain and off, and she needs to figure out which came first. Did she miss gates in the slalom and giant slalom because she is struggling mentally, or is she struggling mentally because she missed gates? These are deep questions that no skier wants to ask, let alone in the middle of the Olympics, but Shiffrin has to answer them fo…