How does the revelation about pollard's blindness in his right eye affect evalution of seabiscuit as a racing horse?

Despite that gift, however, Red continued to have only a middling career. Some of his failures were doubtless the result of an accident he had had sometime early in his career. While exercising a horse around a crowded track one morning, he had been hit in the head by something kicked up by another horse’s hooves. The blow damaged the part of his brain that controlled vision, permanently blinding him in the right eye. “Without bifocal vision,” explains author Laura Hillenbrand, “you don’t have depth perception. So he couldn’t tell how far ahead of him horses were. He couldn’t tell how close he was cutting it. But he knew no fear. He rode right into the pack with one eye.” For the rest of his life, Pollard kept his blindness a secret, knowing that if track officials found out, they would never let him ride.

What passage? there is none