The former Blackpool boss, who brought in 14 players in the transfer window, said that he failed to value the "spirit" of the team that won promotion to the Premier League.
"With the changes in the squad, I have to hold my hand up and say we didn't keep the spirit that got us up, we lost some very important parts of it," the Daily Mail quotes him as saying.
"I think we have tried to change too quickly. Some of the new lads, their attitude, I'm finding it slightly annoying and that ain't right.
"I didn't value enough the spirit of the group [that got us up]. We changed to give us a chance to stay up but lost the spirit of the group."