Saying JJ Watt is playing well is kind of like saying that water is wet. That guy is my favorite non Colt player to watch (when he's not playing the Colts). He plays the game like it should be played.
With Clowney gone, they don't seem to switch Watt much, he will stunt and things but I don't see a lot of opportunities for Nelson and Watt to be matched up. But man, when they do it will be fun to watch.
I'd recommend watching some of his college highlights. I watch a lot of both Big10 and SEC football, and any team that routinely plays ND. Unfortunately or fortunately lol I have several buds that huge Auburn fans, so I've both watch a lot of games, and heard a lot.
Not sure how you can say he wouldn't make a better OG, if you've never seen him play OG.
Here's NFL.com's combine rating on him.
Making it work through athleticism is an incorrect statement and does a huge disservice to Smith. Smith is making it work at tackle by working hard and becoming a tackle. I'm not sure what makes a "true tackle" but to me a guy that plays tackle and plays it very well is as much of a true tackle as anyone else.
As far as AC (or AT if you prefer ) aging... yup, every player on the team is aging so that is not a shock. But he is still just 30 and tackles often play into their mid to late 30s so that is not much of a concern. Not to say they won't draft a tackle in the next couple of drafts, but I doubt they will try to find a starting tackle in the next couple of drafts.