There's small-t tradition, then there's "apostolic tradition." The latter is not "man-made" but given to the church by Christ Himself.
https://www.catholic.com/tract/apostolic-tradition
But apostolic tradition does not appear to be at the crux of what "non-traditional players" is. Whatever it is.
Nope. not going to bite on this one.
Edit: Well, second thought... I'm pretty sure that "apostolic tradition" refers to casseroles at potlucks.