To me it's fairly simple. Rear a greyhound and run it , youd be lucky to hammer it and get to 3rd season in a sound condition. A pure saluki, totally different. Imo . Certain breeds are more robust. But in this game where we are trying to breed the best attribute from various breeds , one litter mate can throw steadier than its sibling. Imho , breed and style along with ground worked is the main factors.