Performance short sizing seems to change every year. Last year their Ultra short L fit me perfect. This year the same exact short is about 4" longer in the legs and wider everywhere else. They must outsource to the cheapest bidder each year and each tailor makes them different.
Actually I have had the sizes vary greatly within the same year. I actually think they have a problem with mis-labeling sometimes. Luckily I have a Performance retail location locally that I can go and try them on at. When I order the same size online they are never right.