Then you have all the dialogue with him and Deniro - and it really drives home the fact that Frank wasn't a thinker. He just followed orders without question. From the army to doing side jobs like the laundry bombing which should have gotten him killed, all the way to taking out Hoffa and losing his family relationships as a result.
All the while with all this great dialogue, Pesci actually steals the scene without saying one word. So many emotions delivered without saying one single word.