A successful Fever season is the 7 or 8 seed (record around 0.500 or slightly below), with Indy beating out Washington, Dallas (sorry, Arike), LA, and Chicago. While I don't necessarily see Indy missing the playoffs as a complete failure, they would be considered a failure if they finish 12th.
Their issues on offense have been well documented, but it's their defense that is absolutely horrific. I've said this before, but I'm not sure why a defensive-minded coach like Christie Sides was not given players who have more of a defensive mentality. While Sides has had her notable issues (continuing to put NaLyssa Smith on Breanna Stewart at this point is major coaching malpractice and the very definition of insanity), she doesn't have much to work with on that side of the ball. She doesn't have a Jackie Young or a Betnijah Laney-Hamilton or a Kahleah Copper that she can slot in at the three position to slow down the opposing perimeter attack from the wing nor does she have a Natasha Cloud, Jordin Canada, or Brittney Sykes who can set the tone defensively from the top of the key. And having a player like Cameron Brink or Shakira Austin instead of NaLyssa Smith would help as well.
The offense was better last year, so we know it can improve. But the defense is just as bad or maybe even worse than it was a season ago. That requires better players.