I haven't made babybacks at home in years. Got them deeply on sale, so I bought up many pounds to cook up for Mother's Day as part of our BBQ meal.
I sort of remember that I used to start them off in the oven, wrapped up in lots of aluminum foil. I'd bake wrapped up for about an hour I think. Discard the foil w/all the fat that had rendered out of them and then finish them on the grill.
This way they were totally cooked already (and very moist) and all I had to do was apply the BBQ sauce to flavor and let the flames do a bit of browning/carmelizing.
Does that sound right? I have this vague memory that if you cook them from scratch on the grill that they overcook too fast and don't turn out as juicy.
BTW, I'm not trying to replicate any kind of long smoked pit ribs, just your quick and easy (but fall off the bone moist) basic home-cooked ones on a regular Weber gas grill.