Well, keep in mind I don't know that much about TNG behind-the-scenes. This is what I know:

Seasons 1-2 aren't so great. Roddenberry is alive.

Roddenberry dies. Season 3 is an improvement.

Someone else takes over. The series takes off for three or four more years, or whatever it was.

As the creator of all this I love him, it just always seemed to me that once he died, TNG stopped being dissapointing and started matching TOS. But based on what you are saying it seems more coincidental. Or we have different views on the series; IMO, like Seinfeld the series got better the longer it went on, although people like early Seinfeld too, and I have to preface that with the fact that I haven't studied them season-to-season like TOS, they bleed together a bit more because there were so many seasons. So I can't say if season 5 was better than 4, I just know that there was a noticeable change of quality around 1991 or 1992, right around when Gene Roddenberry died.