Ole Gunnar Solskjaer saw his Manchester United side comfortably beaten at West Ham on Sunday as a poor run of form continues.

The Red Devils have won only five of the 17 matches played since Solskjaer was given the managerial job on a full-time basis in March.

Here, the PA news agency takes a look at some of the reasons behind the current struggles of the most successful club of the Premier League era.

Squad depth

This point covers a manner of sins.

Although Solskjaer should be praised for clearing out some of the unwanted, high-earning, underperforming players over the summer the required replacements were not ushered in.

Romelu Lukaku, Alexis Sanchez, Ander Herrera all departed over the summer and, even though the trio had varying degrees of success while at Old Trafford, none of them have been directly replaced.

Solskjaer, wise to the ways of United promoting from within, has done just that but the new crop of youngsters are not being integrated into a title-winning side led by Sir Alex Ferguson and with leaders and role models to smooth the process over.

Instead, the likes of Mason Greenwood, Axel Tuanzebe, Tahith Chong and Angel Gomes are being asked to adapt to senior football at a time when United's poor performances, disappointing results and clear lack of quality are being laid bare for all to see.

Injuries

Following on from the first point, Solskjaer has also been unlucky with injuries in the opening weeks of the new campaign.

The 4-0 win over Chelsea on the opening weekend of the season was full of pace, vigour and promise.

But the main attractions of that game have struggled since. Anthony Martial has been sidelined with a thigh issue, Paul Pogba has missed the last three games with an ankle complaint and now Marcus Rashford is set for a spell on the sidelines with a groin injury suffered in the defeat at West Ham.

Full-back Luke Shaw is also missing, while Jesse Lingard has had a spell out and even Greenwood, the 17-year-old who scored his first senior goal in an unconvincing 1-0 Europa League win over Astana last week, missed the game at the London Stadium through tonsillitis.

So, with a squad already struggling for numbers, being hit with such injury issues only compounds Solskjaer's woes.

Confidence

Given their run of form spanning the end of last season and the start of the current one, it is no surprise that plenty of United's players seem bereft of belief.

There was a moment in the West Ham game, with the score still goalless, when Rashford was played in behind the defence – this pacey, strong attacking England international seemingly set free on the Hammers' goal.
But instead he dallied, barely controlling the ball and was easily dispossessed – a small moment but an incident which sums up the current confidence levels across seemingly the entire squad.

Contrast that to Solskjaer's run as caretaker manager when United were beating almost everyone in their path, playing some good football and seeing the smiles return that had slowly turned to scowls under Jose Mourinho.

Only victories – and victories achieved in a convincing manner – can truly address the issue of confidence among the players and those wins are certainly proving hard to come by at present.

Improving rivals

Not all of the problems facing United can be solved in-house.

While their main rivals Manchester City and Liverpool look to be the sides tussling for the Premier League title once again, plenty of other teams in the division have improved over the past two years.

The 'big four' became the 'top six' and now there are clubs outside of that once unpoppable bubble who have designs on getting inside – and even if that is not possible, there are several sides good enough to beat United – as well as Chelsea, Tottenham and Arsenal.

Gone are the days of rolling the smaller teams over – it has been that way for a while – but United are now in danger of falling into the pack of sides who need to summon up all the qualities they can muster just to make sure they can pick up a valuable three points.