David Moyes has struggled since succeeding Ferguson at Old Trafford in the summer.
The Red Devils lie seventh in the table, six points outside the top four and a further eight behind leaders Arsenal.
1 Arsenal 51
2 Man City 50
3 Chelsea 49
4 Liverpool 43
5 Tottenham 43
6 Everton 42
7 Man Utd 37
8 Newcastle 36
9 Southampton 31
Their penalty shoot-out defeat to Sunderland in the Capital One Cup semi-finals in midweek means they are also out of both domestic cup competitions, but Ferguson remains upbeat about the prospects of a team he now enjoys watching as a supporter.
"I'm not writing anyone off," the 72-year-old Scot told BBC Sport.
"Tottenham have started coming forward a bit now, Liverpool are doing very well, Everton are doing very well, (Manchester) City are doing fantastic and Arsenal are top of the league.
"With Jose (Mourinho) you expect (Chelsea) to win games playing ugly, but all these teams are in there. United are in behind chasing."
He added on Sky Sports: "United can do anything. They have got that great philosophy and history, they will always do well.
"I can watch the team whenever I want and I've really enjoyed it. I'm going as a supporter now and instead of suffering with the team, I'm suffering or enjoying it with the fans. I'm really enjoying watching the team play."
Ferguson also dismissed any suggestion United would not give Moyes sufficient time to turn things round.
The former Aberdeen boss says he cannot understand why clubs are sometimes so quick to sack managers, and insists United have a different way of operating - saying they will "absolutely" give Moyes the time he needs.
"Of course they will (stick to their philosophy), they've always been that way," he said.
"There's no need to go down that road (discussing Moyes' future). Everybody knows what Manchester United is, absolutely 100 per cent."
Ferguson does acknowledge, though, that struggling new managers are not always afforded such patience at other clubs, and that's a situation he cannot get his head round.
He said: "I can never understand that.
"They (the club's board) must discuss the qualities of the manager they are going to offer the job to, you must look at his CV, his character, the philosophy he has....surely.
"Now if that is the way they have gone about giving the man the job, why don't they persevere with it?
"So then maybe it goes for a year, then they change, and then they go through the same procedure again. It seems to me so stupid."