Charlotte Zeepvat's book Romanov Autumn presents evidence to suggest that Vyrubova's story of Derevenko abandoning the imperial family is false.
Is that me or Vyrubova's stories are bit suspicious sometimes?
I don't think it's you. She's at best a dubious source, lacking imagination and perspective on the broader issues, and displaying questionable honesty on those topics relating to more private affairs.
I never really bought into the stories of Derevenko belittling Alexei and then abandoning the imperial family. Not only because it's hard to imagine given his character, but if such acts did take place the way Vyrubova suggests how was she apparently the only witness to them?
Knowing how dunderheaded Anna could be, is it possible that she could actually have been referring to Doctor Derevenko and not Alexei's sailor nanny? Not that the good Doctor's loyalty was ever in question - accompanying the family to Tobolsk and traveling with them to Ekaterinburg - but I can imagine him, perhaps, forgetting his place and lecturing Alexei at one point (stress, irritation, etc). I believe he took up the role of teaching the children science while attending to Alexei's medical needs with Botkin during captivity, yes?
It just sounds like one of those stories that might have gotten mangled. That or the product of a personal vendetta she had against Sailor Derevenko who might have, at one time, argued with or insulted her. If the last part is true it actually improves his reputation in my book. "The Cow" deserved a good scolding!