i would say the quote itself - or at least for it to come from a trainer - is probably fictional.
Just about every owner has an aspirational view of their horse and thinks if its not great today - one day it will be. the whole game is built on that gamble.

A trainer has to rely on that feeling to get them to pay $100+ per day to train it.
if they start saying its a donkey - or refer generally to donkeys - well -there goes your 100.


- punters will say it.
- racing commentators will say it.
but trainers - most unlikely.


back to topic though - a good jockey will inspire confidence to the owners and give them something to talk about and in most cases will ride the horse to its best advantage.

in fact if you watch as many races as i do you will see that some rides are for the owners only - to give them hope and keep paying the bills.
the horse will jump moderateley - settle in the last 1/4 of the field and then make a mid race move only to fade in the last 300 - all for the owners.
it could have lobbed along mid field and did nothing and no one would be excited at all.

from a punting aspect - generally a good jockey on a poorly performed horse will improve the prices of the others.

i think that's as far as it could go - they cant carry them.

JMO