Christina Gao's first Senior B assignment was just this year (Nepela Trophy). Agnes Zawadzki did not have a Senior B before her Senior Grand Prix debut in the fall of 2010 (when she was still with Zakrajsek). Brandon Mroz never went to a Senior B until this past spring (his only international assignment last season). The Salt Lake Senior B gave USFS more slots and options starting last year. I assume Wagner has had the option to compete in a Senior B in recent years but has elected not to take it (she was able to test her FS at Japan Open this year, which is not USFS-assigned). ETA: Last season was the first time Flatt only had one initial Grand Prix assignment. USFS often will assign a Senior B to a skater in such cases.