(CNN) For years, reality TV star Donald Trump relished delivering the boardroom version of fate's final judgment. "You're fired!", he blared, and even if he couldn't trademark it, the exclamation became more than a tagline. It was his ethos -- words to live, or die, by. His brand.

But President Trump's time in the White House has revealed a less assertive and assured executive than appeared in the carefully curated, stage-managed world of the "The Apprentice." Personnel, from high-level Cabinet members to low-profile staffers, have come and gone at a stunning pace. The logic informing those decisions has been more difficult to access.

Perhaps it's Twitter to blame. Why stare down and dismiss "beleaguered A.G." Jeff Sessions when it's so much less awkward to spend months berating him , effectively daring him to resign, on social media? Likewise, it's much easier to tweet the news of your secretary of state's dismissal, then call him to chat it over more than three hours later, than sit him down in the Oval Office.

Mike Pompeo, Director of the CIA, will become our new Secretary of State. He will do a fantastic job! Thank you to Rex Tillerson for his service! Gina Haspel will become the new Director of the CIA, and the first woman so chosen. Congratulations to all! — Donald J. Trump (@realDonaldTrump) March 13, 2018

Absent Twitter, the President's tough-guy schtick unravels and recedes. It's almost as if the presence of an audience, be it online or on the other side of the cameras, provides him a certain brand of confidence he lacks in private. The decision to sack Rex Tillerson on Tuesday morning, without telling him face-to-face, is -- as of this hour -- the most glaring example of Trump's sudden-onset diffidence.

Trump had gotten crosswise with Tillerson before, publicly undermining his top diplomat on the North Korea front, tweeting last October that Tillerson was "wasting his time trying to negotiate with Little Rocket Man." It's easy -- and, history tells us, misguided -- to ascribe too much meaning to a message like that. Whether it was posturing or a petulant slap is hard to say, though Tuesday's unceremonious adieu suggests the latter.

Read More