Why can't Manchester United get going under Jose Mourinho? After failing to overcome West Ham United at Old Trafford this afternoon, the Red Devils sit in sixth place in the Premier League table - 11 points behind league leaders Chelsea.
For the first time since 1990, United have failed to pick up a win in four league games in succession at Old Trafford.
Incredibly, during that period, United have had as many as 91 shots but found the back of the net on just three occasions.
There's a serious problem and Gary Neville, who took to Twitter following the game at the Theatre of Dreams, thinks he knows why his former club are failing to produce the goods this season.
Indeed, the ex-England international tweeted that the Europa League has had a detrimental impact on the Red Devils' campaign.
Here's what Neville has tweeted:
United after Europa League
How, then, have United fared in the Premier League this term after playing in the Europa League on a Thursday night? Well, as you can see below, not too well.
Indeed, following a Europa League clash, the Red Devils have racked up just five points from their five Premier League fixtures. In their other eight league fixtures, they have picked up 15 points.
EL: Feyenoord 1-0 Man United
PL: Watford 3-1 Man United
EL: Man United 1-0 Zorya
PL: Man United 1-1 Stoke City
EL: Man United 4-1 Fenerbahce
PL: Chelsea 4-0 Man United
EL: Fenerbache 2-1 Man United
PL: Swansea City 1-3 Man United
EL: Man United 4-0 Feyenoord
PL: Man United 1-1 West Ham
United fans may well be pleased that their side aren't in action in the Europa League this week, but they do have to once again face West Ham in the quarter-finals of the EFL Cup.
Mourinho's side will be without the duo of Paul Pogba and Marouane Fellaini, who both picked up yellow cards against the Hammers.
After the second showdown against West Ham, it doesn't get any easier for United in the Premier League as they travel to Merseyside to take on Everton.
United fans: do you agree with Neville's tweets? Have your say below!