Manchester United manager David Moyes said conceding an injury-time equaliser to Fulham was "as bad as it gets" after his side failed to win for the 13th time in 25 league games this season.
United are now nine points behind fourth-placed Liverpool in the chase for a Champions League place.
The Red Devils had 21 more points after 25 Premier League games last season.
United boss Moyes said: "It's been a bit like that this season. [Sunday] was as bad as it gets. We dominated."
The hosts had 75% of possession and sent in 81 crosses, the most by a Premier League team since 2006.
Despite dominating against the top flight's bottom side, that had lost its previous four league games, United could not hold on to their lead.
Moyes's side have now lost 10 matches overall this season, five at home, and won just three of their nine games in 2014.
Moyes, who said his players were "hurting", added: "There was only one winner in the game, and that was Manchester United.
"I don't know if we could have done an awful lot more. Maybe we could have defended a couple of times a bit better, taken a few more of the chances we made, but we completely dominated and we should have won the game."
Moyes, who took over from Sir Alex Ferguson last summer, saw his side recover from Steve Sidwell's opener as Robin van Persie and Michael Carrick scored to put United 2-1 up with 10 minutes left.
But Darren Bent's header in the 94th-minute led to boos from some home fans at the final whistle.
"Being one down was bad enough. The amount of attempts, chances and play we had was unbelievable. How we didn't win I have no idea," Moyes added.
"It's goals that count. You can have as much possession as you like. We should have scored more. You've got to try and keep making it work. The players tried that and eventually the goals did come and I was more disappointed we didn't make it 3-1.
"It was a bit of carelessness at the back and we could have cleared the ball but didn't and it cost us."
Moyes admitted his team's failure to see out the game hinted at a "mental softness".
But he defended United's approach, despite only 18 of their 81 crosses finding a team-mate and opposite number Rene Meulensteen, a former Manchester United coach under Ferguson until last season, describing their game plan as "straightforward".
"I think if you are going to look at the stats and pick out the number of crosses, you need to look at the number of passes," said the Scot. "I don't think we just went out and crossed the ball.
"And a lot of people would say that one of the big things about Manchester United is that they do play with width, it's in their genes here."
On Wednesday, United visit Arsenal, who slipped to second after Saturday's 5-1 thrashing at Liverpool.