Has Manchester United manager Louis van Gaal been let down by his players?

All but two of Manchester United's regular first-team players are performing worse than they were at this point last season, according to statistics provided by WhoScored.com.

Manager Louis van Gaal is coming under increasing pressure and, after Manchester United's defeat to Southampton last weekend, conceded he was not living up to the supporters' expectations of him.

But are his players letting him down?

We've studied WhoScored.com's statistics-based player ratings and they show that, of players who have made over five appearances this season, only Chris Smalling and Luke Shaw are playing better than they were in 2014/15.

Wayne Rooney, Phil Jones, Marouane Fellaini, Antonio Valencia and Ashley Young have suffered the most significant drop-off in performance levels.

While Chris Smalling's WhoScored.com average rating has steadily increased, Wayne Rooney's has declined rapidly since 2013/14

Paddy McNair - WhoScored rating DOWN 0.45 on last season

Paddy McNair has had few opportunities to impress this season

2014/15 at this stage: 6.75

2015/16: 6.30

Drafted into the side as Van Gaal looked to promote youth prospects into the first team set-up last season, the Northern Irishman has only played a bit-part this season.

Michael Carrick - WhoScored rating DOWN 0.41 on last season

Michael Carrick has been less effective at protecting United's back four this season

2012/13 at this stage: 7.06

2013/14 at this stage: 7.07

2014/15 at this stage: 6.96

2015/16: 6.55

In and out of the team due to injury and squad rotation given his age, Michael Carrick's rating this season is significantly down on the past three seasons. His average ratings were typically consistent in the three seasons leading up to this one. However, this term United have conceded 1.18 goals per game the 34-year-old has played in - up from an average 0.69 goals conceded in his 16 games last season.

Marouane Fellaini - WhoScored rating DOWN 0.71 on last season

Marouane Fellaini's WhoScored.com rating has dropped

2013/14 at this stage: 6.82

2014/15 at this stage: 7.31

2015/16: 6.60

Van Gaal took a liking to Fellaini last season, and the Dutchman was rewarded with an upturn in form from the Belgian's days at Old Trafford under David Moyes. But United have picked up just one point per game when the utility man has featured this season compared to 2.4 when he has not.

Ashley Young - WhoScored rating DOWN 0.48 on last season

Ashley Young has struggled to recapture the form of last season

2012/13 at this stage: 6.93

2013/14 at this stage: 6.45

2014/15 at this stage: 7.12

2015/16: 6.64

Ashley Young seemed reinvigorated by the arrival of Van Gaal last season and returned a much-improved average rating. However, the former England international has been unable to repeat that output this season.

David De Gea - WhoScored rating DOWN 0.05 on last season

David De Gea has maintained his level

2012/13 at this stage: 6.98

2013/14 at this stage: 6.63

2014/15 at this stage: 6.77

2015/16: 6.72

David de Gea posted his lowest average rating for Manchester United during David Moyes' reign. He stepped up in Van Gaal's first season and, despite a marginal drop in his numbers this term, the Spaniard is one of the few United players who can claim to have maintained their form in 2015/16.

Phil Jones - WhoScored rating DOWN 0.84 on last season

Phil Jones has seen his opportunities limited by injury

2012/13 at this stage: 6.58

2013/14 at this stage: 7.25

2014/15 at this stage: 7.56

2015/16: 6.72

Phil Jones emerged as something of a favourite under Van Gaal last season and, when fit, registered a highly impressive 7.56 WhoScored.com average rating. However, injury has limited his involvement this term and his form has dipped as a result.

Antonio Valencia - WhoScored rating DOWN 0.52 on last season

Antonio Valencia has been sidelined with injury

2012/13 at this stage: 6.94

2013/14 at this stage: 7.03

2014/15 at this stage: 7.24

2015/16: 6.72

Antonio Valencia was Van Gaal's first-choice right wing-back at the start of last season, as the manager employed a 3-5-2 formation. While that formation didn't last long, Valencia kept his place in the United defence and secured an impressive 7.24 rating. Rivalled at right-back by new signing Matteo Darmian this season, Valencia's involvement has also been limited by injury.

Juan Mata - WhoScored rating DOWN 0.13 on last season

Juan Mata is short on assists this season

2014/15 at this stage: 6.88

2015/16: 6.75

Juan Mata showed glimpses of his best form last season - most memorably with his scissor-kick goal at Anfield - but a run of 11 league appearances without a single goal or assist this year indicates that his impact on matches has waned.

Ander Herrera - WhoScored rating DOWN 0.19 on last season

Ander Herrera has been in and out of the side

2014/15 at this stage: 6.98

2015/16: 6.79

A player many feel has been deserving of more action under the current manager, Ander Herrera's failure to sustain a run in the side has seen his influence and rating drop from last season as a result.

Wayne Rooney - WhoScored rating DOWN 0.51 on last season

Rooney has struggled in front of goal

2012/13 at this stage: 7.29

2013/14 at this stage: 7.75

2014/15 at this stage: 7.36

2015/16: 6.85

Wayne Rooney had nine goals and nine assists at this point under David Moyes. However, this season, the United skipper has come in for criticism and has just six goals and two assists to his name so far.

Marcos Rojo - WhoScored rating DOWN 0.23 on last season

Marcos Rojo has struggled for regular game time

2014/15 at this stage: 7.38

2015/16: 7.15

In and out of both favour and fitness since his arrival at Old Trafford, Marcos Rojo has rarely disappointed when he has taken to the field - as his average rating shows. Nevertheless, having played under 41 per cent of the possible minutes of league action in that time it's been a frustrating situation for both player and club.

Daley Blind - WhoScored rating DOWN 0.14 on last season

Daley Blind has played in a number of positions

2014/15 at this stage: 7.27

2015/16: 7.13

Played in a number of positions since his arrival, Daley Blind has consistently returned strong WhoScored.com ratings over the course of the past two seasons.

Chris Smalling - WhoScored rating UP 0.09 on last season

Smalling has consistently improved

2012/13 at this stage: 6.75

2013/14 at this stage: 6.89

2014/15 at this stage: 7.09

2015/16: 7.18

Chris Smalling has improved consistently over the past four seasons and has been a key player at the heart of United's defence in this campaign. The centre-back has started more league games than any other player at the club (22) this season.

Luke Shaw - WhoScored rating UP 0.65 on last season

Luke Shaw was impressive before breaking his leg

2014/15 at this stage: 6.71

2015/16: 7.36

After a superb start to the season, Luke Shaw's horrific leg break has been a significant blow to United. Along with fellow England international Smalling, Shaw is the only other United player whose rating has increased from last season.