Top heavy plodder? Lol Penning is one of the best athletes you'll ever see at the position. Physically he has more in common with Terron Armstead than he does Zach Strief. He might not ever be an elite LT but it won't be for a lack of athleticism.
If he stays healthy I think he'll develop the technique needed to be an above average starter but considering the fact that he injured both feet in his first year, I'm not feeling that optimistic about his future.
Overall I think this year I'm going to go with the wait and see approach with the O line. They have looked great on paper for years and I've heard about how great they are but then the season starts and QBs are running for their lives and RBs have nowhere to run.