I'd partly agree on the concentration element.
But like jim says, they are not metronomes and when running against horses of similar ability they'll get beat for various reasons.
Fitness on the day, positioning, jumping and pace of the race are all factors.
The jockey is there to help gee them up at the start and get a good position.
So he's opted to hold back as a tactic cos he thinks the pace is too strong.
He certainly made no effort or asked for more from her in the Irish Champion until the home bend.
She definitely has the speed otherwise she would not have the turn of foot people mentioned when winning the Champion this year off a steady gallop.
It was the "taken off her feet" comment that started this