I always love seeing working actors - supporting actors - not really "stars" - but people that do TV - character parts in movies - suddenly get a great role that really shows what they can do. He was doing it for a good 15 years before Roots came along - and had a great run after that.
I love this kind of thing so much. The job is so, so hard, contingent on so many things, including writing and direction. But I love when an actor you never thought a third second about does something magical. That's when you see it. There is so much craft and ability and talent that sometimes needs the perfect moment to shine.