Four tries in the opening 32 minutes set the tone for the hosts to secure a whitewash series defeat over England in Hamilton, with the contest eventually ending 36-13.
"We started poor and it got worse," Farrell is quoted as saying by Planet Rugby. "The first half wasn't good enough.
"I thought we might have put pressure on in the second half but the first half the All Blacks demonstrated why they're the number one team in the world at the moment. For us to win at this level we need to be better."