OAKLAND, Calif. — The infield is made of asphalt right now. So are the dugouts, the outfield and the stands. Someday this might be home to a baseball stadium, but today the Howard Terminal is little more than a parking lot for 16-wheelers, populated by far more sea gulls than baseball fans. Dave Kaval, the Oakland Athletics‘ team president, walks from the gigantic cranes on the water’s edge to what soon might be the site of home plate.