People on here have mentioned Sacramento, Memphis and Charlotte.
But what about Detroit? Seems like they've honestly underachieved for a while now, and even after making that trade for Griffin (and giving up all that), they are at a pretty distant 9th seed and I'm not sure there is another way for them to improve drastically going forward (considering the picks they've traded and they'd likely need to move contracts just to add others, which would be difficult).
Detroit is in a place that lots of poorly managed teams get to, mediocre purgatory. Denver, Detroit, Indiana, Washington, New York. Always not good enough but never bottoming out. That's depressing but as depressing as having horrid fanbases? Horrid ownership or location issues? Decades of mismanagement and not having winning records? Not having any chance at getting a possible superstar or not having one or having one and never winning?
I don't know. I think Sacramento is probably the most depressing. Brooklyn is and has been massively depressing. Orlando has been awful forever even though they get a great draft pick every year. Memphis looks like things coukd be horrible for years.
Then I think those mediocre teams like Charlotte, Detroit,New York, Denver, etc. are all behind them.
Now thereare some bad bad teams tanking but I have faith they could be good pretty soon, like Phoenix, Atlanta, Dallas, the Lakers.