Why are Manchester United reluctant to appoint a permanent manager mid-season?

Manchester United parted ways with Ole Gunnar Solskjaer after a very poor run in three years. The sacking was imminent and inevitable after a ridiculous 4-1 loss to Watford. 

Former Manchester United player and assistant to Ole, Michael Carrick was appointed as the caretaker manager of the club till a permanent manager is appointed. 

The authority at Old Trafford is being skeptical about appointing a permanent manager mid-season considering the mistake made with Ole Gunnar Solskjaer who was appointed mid-season when his interim position was made permanent following the departure of Jose Mourinho. 

United are considering signing an interim coach till summer when they will have the chance to sign the coach of their choice to take over. Former Barcelona manager Ernesto Valverde is expected to report to Old Trafford as interim manager but was not on the list of the possible permanent manager wanted by united, Zinedine Zidane, Mauricio Pochettino and Brendan Rodgers are top of Manchester United target list but none is currently available until summer.