Everton boss Roberto Martinez felt fatigue was a factor in their thrashing at Liverpool.
Martinez felt fielding the likes of Ross Barkley, Steven Pienaar and Antolin Alcaraz who were short of match fitness played into Liverpool's hands.
Added to their woes was the injury to striker Romelu Lukaku who injured ankle ligaments when Gareth Barry collided with him.
"He has his ankle in a cast. We will assess it but it doesn't look too good at the moment," said the Spaniard of the injury.
"We conceded the opening goal from a dead-ball situation from which Romelu picks up what appears a nasty injury and it seemed we put ourselves in Liverpool's hands and we lost concentration and our normal solid outlook.
"We got ourselves in a position where we lost the game in naive way.
"We were desperate to come here in the derby and be ourselves and give a performance our fans could be proud of but we got ourselves in a position where we played with our heart at times.
"It was nowhere near good enough for our standards."
