Yeah, Beane saw something was Van Rotten so got Ven Denmark (reusing that pun)
You're bang on saying Anderson is not competing with Van Demark. What I can say for sure is 70 played exclusively at G-C on Saturday. 74 played LT and then RT. To me that says, the former (70 - Anderson) is being measured in the 2021 role of Bates as interior back-up-all, and the latter (74 - Van Demark) in the 2022 role of Quessenberry as swing tackle.
Edit: Oh right, Mancz. He's C-only as far as I've ever seen him. And he's been a JAG doing it. I don't except to see him make the 53.