Character changes aren't system changes though especially if it's just value changes and not messing with hitboxes & hurtboxes. But then again, that would be assuming they were doing it in a way that didn't force them to do a ton of work to test different things. That's asking a lot of JP developers in general...
Ah, sorry. I was quickly reading through the posts. All I see was "These tests" and thought it was for all of this pre-release stuff.
I'll assume that beta and stress tests are netplay integrated vertical slices with "current" balance they had at that time.
Event builds are kinda a different matter, since those always have all characters available and do not even have a menu like the beta/stress test ones.
Anyone else think that stress test Ryu was actually more fun than Beta 2 Ryu? Amidst all the nerfs either his parry got less startup or mediums on block got nerfed. From what I tested he was able to parry anything that follows a blocked medium.
EDIT: Usually the way I approach the beta is looking how the current version of the character can be played instead of just looking for nerfs.