To hear President Trump tell it, his administration is, at any given moment, nearly ideal in its composition and capabilities. It is, as he tweeted in September, a “smooth running machine” — never mind that, before the tweet, 15 senior White House and administration officials had quit or been fired and that, in the months since, another eight have joined them. (Since definitions of “senior” can vary, we’re using those officials identified in The Washington Post’s timeline of high-profile departures from the White House.)