Players do not tank. They have no incentive to do so. They are playing for their careers, their next contract, or their next team.
Coaches do not tank. A coach that doesn't win doesn't last long and doesn't get on any other team's short list. Regardless of what camp you are in, by upsetting the Heat in Miami and having a 4-4 record, you have to admit, Brad Stevens can flat out coach. He's getting noticed, in a good way.
The GM, if he's worth his salt, tanks when it's clear that his team can no longer compete for a spot in the Finals. DA unloaded KG and PP to the Nets. He's not through. That said, I believe DA waited a year too long to tank. While we're at it, lets use the more accurate term: "rebuild", rather than "tank". It's what all gererally smart teams do, in all sports, when they are in a simliar situation.
Why are there so many NBA teams in the same boat as the Cs? Let me count the ways...
Too many teams, not enough talent. Expansion money has been a quick fix for the owners.
Too many teams in the playoffs. Byes and best of 3s/5s don't generate as much cash as having #1 vs #8 (or #2 vs #7) in a best of seven in round one.
Since 2002-03 (1st season of the current format), there have been 44 #7 and #8 seeds in the postseason. TWO have gotten beyond the 1st round. The 2006-07 8-seed Warriors upset the 67-win Mavericks. 8-seed Memphis upset the Spurs in 2010-11. Both teams got bounced in the very next round. Conclusion: #7 and #8 seeds DON'T BELONG IN THE PLAYOFFS!!! Yet, these pseudo playoff entries are denied participation in the draft lottery.
My solution, which will never happen, is...
Reduce the playoff field to 6 teams per conference. 1st round bye for division winners. Best of 5 for seeds 3-6.
Get rid of the weighted lottery system. Teams that finish 40-42 and barely miss the playoffs are just as desititute as the team that ends their season at 15-67. This way, GMs have little or no incentive to tank.
Since none of these will ever happen, the only way to rebuild is to tank, tank, tank, until you get lucky and land a true star.
Don't like it? Blame the NBA. They created this environment.