The ease situation is unfortunately common in all of the big three (Simplicity, McCalls, Butterick) and to a lesser extent in Vogue - I typically have to go 2-4 sizes down to get a proper fit. It's kind of egregious in a corset pattern, which should have zero or negative ease (ie, the garment measurements are the same or smaller than your own), but not totally unexpected.My working theory is that the pattern companies assume nobody knows how to measure themselves, and 'too big' is an easier fix than 'too small'. The weird gaping at the bottom front and top back are more inexplicable.