By Chris Cillizza, CNN Editor-at-large

(CNN) -- The hiring of Rex Tillerson as secretary of state was touted as both a coup and a symbol by Donald Trump.

A coup in that Trump had lured the head of Exxon to run his State Department, making good on his pledge to bring the best people in the business world to Washington. A symbol in that Tillerson was an outside-the-box choice that no one saw coming -- just the sort of person (and move) Trump likes best.

"He's a world-class player," Trump said of Tillerson before formally nominating him as the nation's top diplomat. "He's in charge of an oil company that's pretty much double the size of its next nearest competitor."

Just like the hiring of Tillerson was meant to send a message, the firing of Tillerson, which came Tuesday morning, sends one too: The most important thing -- and really the only important thing -- to Donald Trump is how devoted his top officials are to him. The more devoted, the better. Unquestioningly loyal? Best of all!

Tillerson was never that guy. A titan of industry, he just didn't have the bow and scrape in him -- even if he knew that was what Trump required. The examples are legion:

Tillerson refused to back up Trump's both-siderism in the wake of the racially motivated attacks in Charlottesville, Virginia. "The President speaks for himself," was all Tillerson could offer.

Following a report last fall that he had referred to Trump as a "moron," Tillerson refused to issue any sort of denial."I'm not going to deal with petty stuff like that," he said.

Following the nerve gas attack against a former Russian spy in the United Kingdom last week, the White House has pointedly refused to lay the blame at Russia's feet despite British Prime Minister Theresa May doing exactly that on Monday. Tillerson broke with the administration and made clear he believed Russia was behind the attack.

Even as Tillerson was pursuing diplomatic solutions to the North Korea nuclear crisis, Trump tweeted that Tillerson was wasting his time. "I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," Trump tweeted last October.

There's plenty more but you get the idea. Tillerson was far too independent, far too off the reservation for Trump. Even when defending Tillerson, Trump's insecurity about his secretary of state's willingness to get in line was evident.

"The media has been speculating that I fired Rex Tillerson or that he would be leaving soon - FAKE NEWS!," Trump tweeted in December. "He's not leaving and while we disagree on certain subjects, (I call the final shots) we work well together and America is highly respected again!"

"I call the final shots." I mean.

Trump's decision on Tillerson's replacement -- CIA chief Mike Pompeo -- is also telling. Pompeo, a former Kansas congressman, has been a devoted ally to and for Trump since entering the administration. As the Washington Post's Aaron Blake smartly notes, Pompeo has been willing to carry Trump's water since coming into office -- most recently with his decision to meet with the peddler of a widely debunked conspiracy theory about the email hack of the Democratic National Committee.

"We are always on the same wavelength," Trump said of Pompeo before jetting off to California on Tuesday morning.

Out goes someone Trump couldn't control. In comes someone he knows he can.

We tend to overthink things when it comes to Trump, ascribing his various hirings, firings and other machinations as part of some grand plan that only he can understand.

The past year-plus suggests that there is no grand plan and that the simplest explanation is probably the right one. Which means this: Trump got sick of having someone working for him in such a senior role who he didn't think respected him -- Trump never really got over the the "moron" comment -- and who wasn't willing to pledge full fealty to him.

So, he found someone who would.

The rise and fall of Tillerson mirrors Trump's own arc when it comes to how he will run his White House and with whom he will surround himself.

Tillerson was the crown jewel of Trump's Cabinet -- the living, breathing, walking proof of how Trump really could bring the best and brightest from the business world to Washington to work on the country's behalf.

That he never really fit in -- and that he was at daggers drawn with Trump almost since the jump -- shows that Trump was never really committed to the idea that Tillerson seemed to embody: That the President would lean on and listen to highly successful and skilled people he brought into his Cabinet.

Trump is, has been and always will be sui generis. The Trump administration is Trump. And , increasingly -- from last week's resignation by top economics adviser Gary Cohn to this week's firing of Tillerson -- Trump seems to be embracing that idea.

"I am really at a point where we are getting close to having the Cabinet and other things that I want," he told reporters Tuesday morning.