My mother always put the raw meatballs in her sauce. Our Italian neighbors never did. They fried or baked them first………depending on how many they were making. I find the sauce just as good either way. My Italian lady friends told me that the amount of cheese and the number of eggs that you put in the meat was the key to tenderness. I really have no idea but I do them the way our neighbors did and I make terrifc meatballs.[:D]
I usually put my uncooked meatballs into the sauce and let them cook that way also….sometimes I bake them first if I use ground beef instead of chuck because of the fat in the sauce….you just cant skim all the fat off the top….