The swing shape is cleverly created through a series of eyelet increases and short rows, which gives a knitter something to look forward to during all that stockinette.
One thing I did struggle deciding was which size to knit. The total bust measurement is different than that of a standard cardigan, due to the draped lapels. And, there weren't any suggestions regarding the amount of ease that a knitter ought to choose. I chose to use the back measurement (a) and hoped the rest would fall into place, and it seemed to. If I knit it again, I might try a size smaller to see how big the difference is.