Season 4 might have been the year of Family, but it was also the year of awesome development of the relations between the Federation, Klingons, and the Romulans. It expanded the Star Trek universe to where DS9 could take it and run with it. Hell, everyone calls Season 4 the year of the family, yet those were only in the first few episodes of the season. Season 4 was much more about expanding the good stuff TNG laid in the previous 3 seasons than it was about Family.
I just saw "The Mind's Eye" and I had forgotten how awesome this episode was. The Grim music, taking one of the more innocent regular characters, laying the groundwork to Redemption, it's like watching this episode, TNG tried to do arc storytelling in Season 4 and somewhat succeeded. I think the worst missed opportunity this series had going for it was it never followed up the brainwashing. After Redemption II, it seemed to drop the Klingon/Romulan arc almost entirely, yet just imagine if those threads were weaved throughout the series and we did get a Brainwashing follow up. With that, and more contact with the Cardassians, this series could have been even better than it was.