Chalk it up as "your milage may vary". Speaking personally, I do agree with what Tosk says above, and feel that there was definitely a broad dip in quality in the last two seasons, as if in some ways the team was becoming creatively bankrupt in terms of what they could bring to TNG. And as Bad Atom says, it is also not unrelated to DS9 just starting up. It's perfectly natural that a greater amount of the available resources were going towards the new boy rather than the established favorite.
To be fair, Berman and Pillar predicted the situation. One of the very first memos they wrote to the TNG team going into the sixth season was an attempt to dispell the feeling that DS9 was going to somehow supplant TNG, and they emphasised that they wanted both writing teams to work together in sharing ideas. But in practice it was hard for them to avoid a little "brain drain".