EPL: Five things that went wrong with Arsenal this season

London: Arsenal's 2-1 defeat by Manchester United at the weekend left them 15 points below Premier League leaders Chelsea after their worst start to a season in 32 years.

These are five reasons why Arsene Wenger and his boys made such a disappointing start.

Injury blight

Despite acquiring the services of renowned fitness coach Shad Forsythe prior to the start of the season, Arsenal's players continue to display an unusual susceptibility to injury. Olivier Giroud and Aaron Ramsey have spent significant periods of time on the sidelines this season, Mathieu Debuchy, Laurent Koscielny and Mesut Ozil remain unavailable, and Theo Walcott is still being eased back into action after sustaining knee ligament damage in January. Things got worse against United, with Jack Wilshere and goalkeeper Wojciech Szczesny both obliged to hobble off.

Incoherent transfer policy

The pre-season signing of Alexis Sanchez and early season arrival of Danny Welbeck left Wenger with an enviable collection of forwards and attacking midfielders to choose from, but Arsenal's rearguard appears understaffed. Wenger's failure to replace Thomas Vermaelen, who was sold to Barcelona, has left Arsenal short in central defence, with left-back Nacho Monreal obliged to fill in alongside Per Mertesacker in the absence of Koscielny. Arsenal also lack an authoritative holding midfielder, obliging Mikel Arteta to occupy a role to which he is not ideally suited.

Defensive shakiness

Wenger observed after the loss to United that his side "lack a bit of maturity defensively", and it has become a recurring problem. Arsenal have kept only three clean sheets in the league this season -- against Aston Villa, Sunderland and Burnley -- and have lost nine points from winning positions. They let a 3-0 lead slip in a 3-3 draw at home to Anderlecht in the Champions League earlier this month and also failed to defend their advantage in a 2-1 defeat at Swansea City, flooding forward after going ahead in the 63rd minute and getting caught on the counter-attack. Former Arsenal defender Martin Keown has described the team's gung-ho tactics as "criminal".

Big-game frailties

Arsenal's poor record against the other leading teams in the English top flight is well documented. They lost heavily at Chelsea, Liverpool and eventual champions Manchester City last season, shipping an extraordinary 17 goals in the process, and have won only one of their last 15 meetings with United, losing 11. All four of the teams they have beaten in the league this season currently reside in the Premier League's bottom seven.

Ramsey off the boil

It would be unfair to attribute too much importance to Aaron Ramsey's loss of form, but Arsenal have unquestionably missed the Welsh midfielder's goals. Ramsey started the 2013-14 campaign like an express train and finished the season with a career-high total of 16 goals, but he has found the net only three times this term and is not wielding as much influence as he did 12 months ago.