Keown insisted he did not sense any "fight" from the United players during their frustrating 0-0 home draw with Southampton on Saturday.
He told BT Sport: "I think he's lost the players. I didn't sense any fight from the players.
"There's work to do with these players to get back on board [with them]. There doesn't seem to be the harmony here that I would have seen at the start of the season.
"I expected much more from Manchester United today, at least to get three points in the bag. They've been professional to this point in the season and now the wheels have come off.
"The top four is not a given for them, it's going to be very difficult with City running away with it, but I'd be very interested to see where [Mourinho] goes with this one because he seems to have lost the players today."