David de Gea thinks that Manchester United's nightmare start to the 2019-20 campaign is partly down to a "lack of quality" in the starting XI.
The Red Devils have slipped to ninth in the Premier League table, posting their worst points tally after 13 fixtures in the top flight for 33 years.
A 4-0 win over Chelsea on the opening weekend raised expectations after last season's sixth-place finish, but United have only added three more wins since then, while also recording five draws and four defeats.
Ole Gunnar Solskjaer's side are already nine points adrift of fourth-place Chelsea and cannot afford to lose any more ground in the race for the final Champions League spot.
Ahead of a must-win home fixture against Aston Villa on Sunday, De Gea has defended the squad's work rate, but also conceded that "certain areas" need addressing for United to start climbing back up towards the top of the table.
Pointing to a horrendous first-half showing during the 3-3 draw at Sheffield United last Sunday, De Gea told Sky Sports: "The team is what it is, and results are what they have been recently.
"It's true that the first half was horrible, probably one of the worst this year. The reaction of the team in the second half was important, but it's not enough.
"We should win these type of games to be on top, we need to win four or five games in a row to be at the top, but at the moment the team is not playing so well.
"We're giving it everything, we're trying to get those big wins that can put us high up in the table, but the truth is at the moment we're not consistent enough, there's much to train and much to improve.
"I don't think it's through any lack of effort, the boys are leaving everything out on the field in training and games.
"You could point maybe to a lack of quality in certain areas, but certainly not a lack of fight."
The Spain international is well into his ninth season at Old Trafford, having arrived in Manchester from Atletico Madrid back in 2011.
De Gea was heavily linked with moves to Real Madrid and Paris Saint-Germain earlier this year, but put an end to any speculation over his future by signing a new deal with the Red Devils in September.
The 29-year-old is now set to remain at the club until 2023 and still feels "thrilled to be part" of one of English football's most successful clubs.
"The truth is I feel at home here," De Gea said. "There are times when I am in Spain and I'm really looking forward to coming back here, at home in Manchester.
"We've been here for a lot of years and I feel like people appreciate me here, I've made a lot of friends and I'm thrilled to be part of this club.
"It's been a long time that I've been playing here and it's not an easy thing to keep playing at the highest level and to maintain that level.
"I personally hope that we can get more accolades in years to come by working hard and playing to that same high level."