Hemingway's thesis about bullfighting--it has become decadent as subordinate aspects like capework or the placing of banderillas, things once considered the preparation of the bull for the crucial moment of killing, have become instead ends in themselves--is also his thesis about writing.
The rising emphasis on decorative capework and the concomitant evasion of death/truth in bullfighting represents, in the book's allegorical economy, the rising emphasis on decorative style and the concomitant evasion of death/truth in writing.
Chapter Fifteen, one of the book's most crucial, addresses this theme through another discussion of the changing part capework plays in the corrida.