Shocked to see how high that turn over is. I wonder if this has always been the case for NBA coaches where 3-5 years seems to be cliff or if it's our current microwave society putting pressure on the GM to turn things around instantly.
There is always a lot of turnover. I mean even looking at the all time win leaders, they moved around a lot. Don Nelson had 5 different jobs (4 teams). He was with the Bucks for 10 seasons, but never more than 7 years in other stints. Lenny Wilkins moved around a lot. Even Riley wasn't with the Lakers as long you would think 81 to 90.
Sloan, Pop, and Red are the only guys to coach a team for at least 15 consecutive seasons and there aren't many others that even hit 10 seasons with the same team.
On top of that, there's 14 teams that don't make the playoffs every year, and a few more that get bounced earlier then expected. So that's over half the league right there that might be looking for a new coach at any given time.
Also, except for the rare perennial power houses, it's not the same team in the playoffs every year believe it or not. About 40% of the teams in the playoffs this year were in the lottery 3 years ago, and that number moves closer to 50% if we go back 5 years. Going back 3-5 years we had teams like the Nets, Knicks, Sixers, and Lakers in the playoffs, and teams like the Warriors, Clippers, Cavs, and Raptors as laughing stocks. There's only 3 teams in the entire league who have been in the playoffs every season for the last 5 years (Hawks, Spurs, and Grizzlies).
There's a lot of teams losing every year, and many of the good teams don't stay good for long, so you can see how a lot of teams might want to try out a new coach.