McCullough has joined League Two outfit Tranmere Rovers on loan until January 2, with McCann – keen for his midfielders to rotate and be interchangable in their positions in the middle of the park – believing that the 24-year-old does not fit into the playing style he is attempting to cultivate.
McCann, whose side registered a goalless draw with Shrewsbury Town on Tuesday evening, said: “I just felt that he did not fit the way we played. I love Luke, he is a great lad and there were a lot of clubs who wanted to take him and he said that he wanted to go to Tranmere.
“It was really a case of wanting my (midfield) three moving and rotating. You have seen over the four or five games we have played that Ben (Whiteman) does not sit in a number four position, he moves around the pitch.
“And they all take positions off each other.
“I felt that Luke is more of a defensive midfield player, who does not move out of his slot.
“Of course, there are games where you might need one of them. But with the way we are playing at the minute, we want the movement and rotation and Luke did not fit that.”
In sanctioning McCullough’s exit, McCann says that he was also acutely aware of the fact that the player was in grave need of a run of games after spending the majority of the past two seasons out due to serious injury.
McCann, who confirmed that Rovers are close to completing another midfield/attacking signing who will ‘provide something different’ to add to their existing options, said: “The boy has been out for two years and there is no point him sitting on our bench and stand every week.
“It was only fair on Luke that he goes and plays some games.”
Midfielders Herbie Kane and Tommy Rowe will be assessed ahead of Rovers’ weekend game with Portsmouth after picking up knocks.
Defender Joe Wright, who came off with a mild bout of concussion late on in the second half against Shrewsbury, will also be monitored in the next few days.
Rovers have allowed trialist Romario Vieira to leave the club.