be a workhorse, not a show horse

To put in a lot of work or get a lot of results without seeking or receiving much attention or publicity for it. Used especially in reference to politics. The young senator from Vermont has proven a workhorse, not a show horse. She's achieved vast legislative victories over the years but is rarely in the spotlight. Though his highly publicized campaign was one of the biggest spectacles of the year, his actual time in office has proven that he is a workhorse, not a show horse. Of course Ted won't take any credit for our department's success. He's always been a workhorse, not a show horse.