Pulitzer Prize winner Jane Smiley, in Sunday’s New York Times, makes this point in her “The Rail” column (linked here) about Zenyatta:
Her stride angle is the same as Secretariat’s, as measured by Bob Prichard of the Somax Performance Institute. But Zenyatta lures us in with personality. We love that she wins because she convinces us that she is more than a running machine. She has a palpable desire to run. She is a character, and when I am rummaging around on the thoroughbred pedigree Website, I wonder: is it nature or nuture? …
Zenyatta is a rare phenomenon, but we can still use her as an example of the pleasure we take in the old, sound bloodlines, the pedegrees of the horses that took time to grow up and kept running even when it would have been more profitable to send them to the breeding shed. … John Shirreff is patient and honest. He does not use an excess of medications or use illegal drugs on his horses. He did not push his big mare to the races — Zenyatta was nearly 4 years old when her remarkable streak began, and now at 6 she hardly looks worse for the wear. ….
She unleases those longer-than-the-longest strides, and she flows like a shark around or through her company. Sometimes, she wins by a few lengths, sometimes by a neck. but the look on her face always indicates that you were the one who was worried, not her.