Saturday's game is the third time this season United have faced opponents who have just sacked their manager.
And Ferguson finds Reading's decision to axe McDermott perplexing in the extreme.
"I never understand football," said Ferguson. "If they had done it in December or January maybe I would have understood it because he could have brought players in.
"Brian McDermott has done a good job given the outlay. He spent something like £1.2million and got in £7.4million and got them promoted to the Premier League.
"He was manager of the month in January - I hope I am not manager of the month this month."