What is the proper way to bake meat balls in the oven?
One technique I have used is to support the meatballs with toothpicks over a muffin tin. This allows the liquid to run off and collect. I forget which food network show I learned this from, but it has been a good technique for me.


  I'm trying to minimize the outbound
  loss of fluids


As fat is rendered to liquid it has to go somewhere. It is either going to be absorbed into something (like dry bread crumbs) or it will leave in the form of 'juices' oozing out of the meatball. I have to disagree with @Bruce's "breadcrumb slurry" as that adds an additional saturated element that leaves no place for fluids to go (other than to leave). Dry breadcrumbs will absorb those juices before they escape. One way to put that juicy goodness back into your dish is collect those juices, mix with some butter and an equal (total) amount of flour to create a rue and then either add milk to that to create a cream gravy to serve over the meatballs or add it to a tomato sauce to thicken the sauce in infuse the meaty/juicy goodness to the sauce and so it will stick to the pasta :o).