I have breed and broken in my own on occasion. and mine have not always been the fastest .. but I tell you, they can win for others purely on manners at times. Dont underestimate a well trained animal, that is fully fit. A horse that will move in that split second will save a second.
One that will relax, one that will go forward, one that will keep trying. all these things will make a difference.
I remember reading an article many years ago, about 2 x T/Breds Tullock and his full brother (cant remember name) they say they had the same speed, but if you had them at a tea party, tullock, would come in serve the cakes and pour the tea - the brother would storm in knock it all over and stand there wondering what happened ..
It takes a lot to be a good trainer, and it helps to have horses, that want to help you.
you dont often hear of a person saying that there champion horse wont go forward, wont load in the float, you cant drive it, and its as mad as a cut snake..