nose, durability, improved averages of throwing dogs that stay till dug. breeding won't improve a dog thats already working, improve the ability and percentages of the ones to come.
In a nut shell mate, your full of shit .
Why is he full of shit? It's like saying in the Bulldog world over here back in the day if a line was throwing game dogs how can they be improved on if they are game? There was still dead game dogs all those years back over here in the British Isles but only a fool would deny that the yanks have bettered and improved our dogs that were shipped over.