He is one of the most powerful OL in football. I would go so far to say he is the most powerful OL we have had since Larry Allen.
I used to be impressed when Leary would steer or Martin would stand up mammoths like Suh and Vea. Smith gets push on them.
Then there is his agility. His ability to recover from mistakes is what allows him to be average in pass protection. He takes false steps or is slow off the ball or to recognize but it doesn't matter because he can move quickly enough to get leverage position.
There are a lot of players who are fun to watch on this team. He is definitely one of them.