Evans gave his reaction to the drubbing in his Gaffer on a Sunday feature, speaking to the clubs website.
"The performance in the first 30 minutes was totally unacceptable. Our defending was shambolic and our willingness to match the effort of the Port Vale team was shocking.
"As the manager then I will take full responsibility for such a performance and set about putting it right. The match was over at half-time and the only slight comfort we can take is that we dominated the second period but again poor defensive errors made it impossible for us to salvage anything.
"We have a good squad of players here but a few of them now need to step up their performances or move on. I did not get much sleep and I don't think the players will have done either. We need to look clearly at the mistakes, ensure we eradicate them in the future and learn very quickly.
"This is a tough league and the results showed that again yesterday, it is time to work hard now rather than feel sorry for ourselves, that is what weak teams do, the strong teams get in the trenches and fight."
Evans added: "Port Vale has gone now and it is about getting ready for Torquay United on Saturday. We know the importance of the next three matches as good results in them will see us comfortably in the top three of the league, a place where we need to be."