Big Beef Meatballs with Bucatini

Name: Big Beef Meatballs with Bucatini
Ingredients: 1 1/2 pounds ground sirloin; 2 small to medium yellow onion, 1 grated and 1 finely chopped; 6 cloves garlic, chopped, divided; 1 egg; 1/2 to 2/3 cup Italian bread crumbs, a couple of overflowing handfuls; 1/2 cup grated Parmigiano-Reggiano, plus some to pass at table; 1/4 teaspoon ground allspice or nutmeg; 3 tablespoons capers, drained and chopped; 2 tablespoons chopped sage leaves, 4 to 6 sprigs; A couple generous handfuls flat-leaf parsley, chopped, divided; Salt and pepper; 3 tablespoons extra-virgin olive oil, plus some for drizzling; 1 pound bucatini (thick, hollow spaghetti); 1/4 pound pancetta, chopped; 12 baby portobello caps, (crimini mushrooms), chopped; 1/2 cup dry red wine, eyeball it; 1 cup, (8 ounces), beef stock; 1 (28-ounce), can crushed tomatoes, Sam Marzano if available