I don't agree with your interpretation of events. I do agree that he did good work on TNG. No argument there. DS9 never had good ratings, though, and saying Voyager was the number one show on UPN is like saying that the sun is the number one rated sun in our sky. UPN had no other shows. And Enterprise had the same problems as Voyager - low ratings.
There are no events to interpret,
Star Trek was a financial success under Berman's stewardship.
Star Trek: Voyager was put on UPN to give the network some credibility... I don't think anyone expected it to draw 20 million viewers a week on the two dozen low-power UHF stations that made up UPN. What exactly did you want from
Deep Space Nine? Yes it bled viewers but if you look at it as a continuation of
The Next Generation it was going too. Not many shows that are on the air for 10 - 20 years have continued audience growth (not to mention that it was competing with both TNG and VOY). But it continued to be the number one syndicated show during its run and that was still so even though many stations dropped it because Paramount was overcharging for rights fees.
Now you can debate whether or not it was a creative success under Berman. Some think it was, others not so much... but that comes down to personal taste.