I'd like to suggest that the PTR be re-opened for the testing of Ranked role lists for season 5. Currently, role lists are being tested in the main game, which has a few flaws in it.
The first of these issues is that people are constantly complaining about how bad the current list is in-game, making things unenjoyable. If testing was moved to the PTR, people would go in knowing that things aren't likely to be perfect, and would likely spend less time endlessly complaining and more time figuring out exactly what the issues are and suggesting them on the forum.
The next issue is that the current mode of testing is plagued with the typical issues that you find in Ranked. People still throw left and right, and it makes it harder to analyze the list being tested. Moving testing to the PTR would help to gatekeep throwers from the tests.
Moving testing to the PTR also means that people can post feedback and suggestions about the role lists in the PTR section of the forum, rather than clogging up the other sections of the forum.