Opinion: With McAleenan’s ouster, leading Homeland Security could be the least-secure jobs in D.C.

News, of course, is defined as that which is new. Which might explain why the resignation Friday of acting Homeland Security chief Kevin McAleenan barely stirred the surface of President Trump’s infamous swamp.

When you’re the fourth person in less than three years — 999 days and counting — to leave the same top government job, that’s less of a news event than it is following a new tradition.

To illustrate, these are Trump’s former secretaries (and acting secretaries) of Homeland Security:

Former Gen. John F. Kelly lasted seven months before being promoted to White House chief of staff; he was replaced by Deputy Secretary Elaine Duke, who held the acting title for four months before making way for the Senate-approved Kirstjen Nielsen, who lasted 16 months (and oversaw Trump’s horrific family separations policy) before she was bounced in favor of the “tougher” McAleenan, who lasted six months (plus a little more until he formally leaves office).

It’s enough to make your head spin. And yes, the directors were evenly split between Senate-confirmed and acting. So whoever Trump appoints — reportedly sometime this week — gets to be the tiebreaker.

McAleenan’s departure offers yet another data point for future historians as they assess how far down the competency scale Trump will rank among U.S. presidents (don’t bother asking him; the nation already knows what he’d say).

Trump reigns more as a petulant child than a seasoned manager — perhaps a function of running his relatively small family business for so long, an environment in which his word was supreme. But that’s not the right training for running a massive bureaucracy and navigating diplomacy, or dealing with co-equal branches of government where people have the responsibility to say no when necessary.

And Trump doesn’t like being told “no.”

So McAleenan’s departure reflects once again Trump’s ego-driven approach to management. Rather than appointing top-level officials to jobs that require Senate confirmation, Trump names “acting” officials as a strategic move. Such tenuous holds on a position make it harder to speak truth to the boss, lest you get fired. And with this president, even playing the toady can get you fired.

“It’s easier to make moves when they’re acting,” Trump explained to CBS’ “Face the Nation” in February. “I like acting because I can move so quickly. It gives me more flexibility.”

Maybe. But it makes for weaker management. “Acting” top executives rarely get the kind of internal support from career employees that Senate-approved leaders enjoy, since everyone knows it’s just a matter of time before the current top dog gets run off. It also reduces the caliber of the pool of job candidates, since few highly qualified people would risk derailing a career over a job with an uncertain length of tenure.

Especially under a boss who is so mercurial that it’s difficult to understand what policies you’re supposed to be implementing. Or, in McAleenan’s case, when you can get fired for doing exactly what the boss wants.