“Sparrow had a tennis racket” is the counterpart to “Bianca had a sketchbook” — there to establish that Sparrow plays (or played) tennis as a hobby, which never comes up in the story again.

Maybe it’s for the best. I don’t actually know enough about sports to get much narrative juice out of Sparrow-the-tennis-player. And Bianca-the-artist could’ve gotten embarrassingly self-referential.