Complex sentence: Only the exterior façade of the old stadium remained, with concessions, concourses, level loge boxes, and seating areas being reconstructed, essentially creating a new ballpark within the shell of the old park.
Split into simpler sentences: Only the exterior façade of the old stadium remained, with concessions, concourses, level loge boxes, and seating areas being reconstructed. The improvements essentially created a new ballpark within the shell of the old park.