For most of my basketball-watching life, I’ve operated under the assumption that NBA executives work under extreme job-security pressure. I presumed they entered every season knowing that if they messed up a couple of decisions, or perhaps just got some bad luck, they’d wind up with their heads in a noose.

Then the 2006–07 campaign came along and challenged all of my assumptions on this topic. Oh, sure, a couple of guys still got replaced — fare thee well, Steve Patterson and Bernie Bickerstaff. And the remaining ranks may thin by one or two more after the season, with Seattle’s Rick Sund among the most likely victims.

But the remarkable feature of this season hasn’t been the folks who lost their jobs, but the guys who have kept them. Despite milelong track records of failure and litanies of glaringly obvious mistakes, several of the league’s biggest nitwits seemingly have earned lifetime tenure with their organizations.

Take Kevin McHale, for instance. I’m still reeling from the shocking news report yesterday that the bumbling president and general manager of the Minnesota Timberwolves apparently has an open invitation from owner Glen Taylor to come back this season. Knicks fans may not believe this, but McHale’s reign of idiocy in the Land o’ Lakes makes Isiah Thomas look like Red Auerbach.

Do you realize that McHale signed Trenton Hassell, Troy Hudson, Marko Jaric, Mark Blount, Eddie Griffin, Mike James, Justin Reed and Mark Madsen to long-term deals … and that they will make a combined $40 million this year … and that not one of them would start for the Knicks, who themselves are a lottery team?

Minnesota has the league’s sixthhighest payroll and one of the best power forwards in the history of basketball in Kevin Garnett, but it is 32–45 and faces its third straight year in the lottery. Of course things might be slightly better if McHale hadn’t had the chutzpah to fire coach Dwane Casey after an overachieving 20–20 start that most observers considered a pleasant surprise. Casey’s replacement, Randy Wittman, has gone 11–24 since taking over.

At least the T’wolves have Garnett. Were it not for him, this team would have been the laughingstock of the league a long time ago. But it will be there soon enough — Garnett has an opt-out in his contract after next season and is likely to demand a trade this summer.

Then there are the two Billys — Mr. King in Philadelphia and Mr. Knight in Atlanta. Knight has had his hands partially tied because of a raging ownership battle that we hope will be settled by this off-season, but that hasn’t stopped him from making numerous mistakes — including the unique accomplishment of passing on consecutive Rookies of the Year in the draft in order to select an overmatched ACC forward named “Williams.”

In 2005 it was Chris Paul, who was exactly the up-tempo point guard the Hawks needed to get the rock to Josh Smith and Joe Johnson. But Atlanta took Marvin Williams instead, who has struggled to compete against stronger forwards at the pro level. Amazingly, Knight repeated his mistake this past June, taking limited banger Shelden Williams one spot ahead of likely Rookie of the Year Brandon Roy. Maybe it’s a good thing that he’s already traded away the Hawks’ first-round pick this year, unless it ends up in the top three — it’s a down year for Williamses anyway.

But having missed out on Paul and Roy, Knight doubled-down on his point guard gaffe by signing a fading Speedy Claxton to a multiyear deal for the midlevel exception and making a head-scratching trade for Anthony Johnson at the trade deadline. That deal cost the Hawks a high second-round pick, provided Dallas several million in luxury tax savings, and offered no appreciable impact to the Hawks that might offset the cost. Those two will join Lorenzen Wright, Esteban Batista, and John Edwards in the pantheon of great Knight talent acquisitions.

Yet, he’s as secure in his job as he was the day he arrived in Atlanta (and almost immediately started tearing apart the roster, I might add) … just as his namesake Mr. King is in Philadelphia. This Billy made a series of wretched contract decisions that left the Sixers with the league’s fifth-highest payroll, yet one of the league’s worst records.

King’s affinity for giving generous contracts to second-tier players rivals that of McHale: B-listers like Kenny Thomas, Eric Snow, Kyle Korver, Brian Skinner, Willie Green, and Sam Dalembert all got multiyear deals in the tens of millions during his reign. Ultimately those moves left Philly capped out and talent dry, forcing a desperation trade for Chris Webber and, when that failed, the disposal of both Webber and Allen Iverson earlier this season while the club tries to rebuild.

Here’s the amazing part: The Sixers left King at the helm to oversee the rebuilding. I mean, if a stockbroker lost all your money, would you put him in charge of earning it back? If a mechanic screwed up your engine would you take it back to him for the repair? Yet the Sixers have shown no inclination to dismiss King, and in fact, brought on his old pal and fellow personnel expert Larry “let’s get Steve Francis and Jalen Rose in here pronto” Brown as a consultant.

McHale and the two Billys are the most egregious examples, but their teams aren’t the only ones that have given a coach or executive carte blanche to keep screwing up the franchise (don’t even get me started on Elgin Baylor). For local fans, it presents an interesting, if alarming, trend because Isiah Thomas is far from the only one getting a free pass.

In fact, compared with these other fools, Thomas, one could argue, has at least done something to merit his recent contract extension. Although prone to hubris as an executive, Thomas is a halfway decent coach, and the Knicks would probably be heading back to the postseason were it not for the torrent of injuries that hit right after he inked his extension.

Obviously, the bar should be much, much higher, especially for a team in a weakling division that’s spending double that of most opponents. But looking around the league, should we really be surprised? Unfortunately, several franchises seem to be operating in a brave new world where incompetence is rewarded roughly as well as success. That Thomas is far from the worst example is a sad commentary on the extent of the problem.

jhollinger@nysun.com