The Blues dropped to fifth as Everton's 2-0 win made it four
games without victory.
And boss Villas-Boas admitted Chelsea's low-key performance -
with Fernando Torres again struggling in front of goal - was
unacceptable.
Steven Pienaar and Denis Stracqualursi downed the Blues to leave
Villas-Boas saying: "I think today was one of our worst games of
the season, if not the worst.
"In our performance today we are short of anything positive. "It
is a difficult day for us, we take out a lot of negatives from this
game."
Blues fans chanted 'You don't know what you're doing' when
Villas-Boas took off Michael Essien just before Everton's 72nd
minute clincher.
And the Portuguese - whose predecessor Carlo Ancelotti was
sacked at the same ground last year - said: "It is part of the
job.
"At the moment we are sitting fifth in the league and it is not
enough for us."
He denied Chelsea's performance was hit by speculation following
owner Roman Abramovich twice visiting the club's training
ground.
He added: "We suffered very early in the game. We then had the
control of possession until the end of the first half but couldn't
create enough chances.
"In the second half the game was divided between the two teams
and we had no clarity.
"We were not able to create chances. In the end that lack of
clarity punished us."
Villas-Boas insisted £50million striker Fernando Torres -
goalless since September - will be given all the time he needs,
even once Didier Drogba returns from the African Nations Cup.
He said: "He is trying a lot to get his chances and to shoot at
goal.
"Whatever time it takes, we will continue to pursue his
confidence and full form until he eventually finds the back of the
net."
Everton chief David Moyes, whose side beat Manchester City in
their last home match, said: "That was a great result.
"There were good parts of the performance as well but the
strange thing is I think we can play much better.
"I think we will play better once we get more confidence as the
wins take us a long.
"We got off to a great start with an early goal, which gave us
something to hang on to, but we wanted it.
"We had to ride our luck on a couple of occasions but in the
second half we didn't look like we were going to
concede."
Moyes praised Pienaar - back on loan after a poor first year
with Spurs.
He said: "He got clapped by everyone at the end. Some of the
stuff he did was terrific.
"I said to him at the end it was like he had never been away.
Sometimes clubs just fit players and maybe that is the case. Maybe
this just suits him."