My thoughts about Willoughby's first appearance as a young man out hunting, a sportsman, being used as a metaphor for his behavior as well as an activity which he loved would seem to be supported by Elinor's words: "The whole of his behaviour," replied Elinor, "from the beginning to the end of the affair, has been grounded on selfishness. It was selfishness which first made him sport with your affections --..." This strengthens my belief that JA purposefully introduces Willoughby as a hunter.