Once again, Manchester United had to come from behind to win it. It is getting to the point where United only burst into life when the clock ticks into its thirtieth minute and the opposition are a couple of goals to the good.

Their last three home games have followed a similar pattern; a clumsy and careless start is followed by an opposition goal which stuns the crowd. From that moment, United slowly click through the gears and find an equaliser. Then, as if the first third of the game is erased from their memories, they go on to control the match with ease and effortlessly cast aside the opposing team. Obviously, the 3-2 defeat to Tottenham didn’t  the trend. However, Tottenham will be the first to tell you that they were fortunate to leave Old Trafford with their three points intact.

Last Saturday, Stoke silenced Old Trafford with a second minute opener. They then should have capitalised on United’s dreadful start by going two up, but Jonathan Walters was foiled by David De Gea. A few minutes later, Robin Van Persie’s inch-perfect cross found the forehead of Wayne Rooney who guided it into the back of the net. The game was as good as gone after that for Stoke save for a Michael Kightly goal that was swiftly ruled consolatory by another Rooney goal.

Likewise, the first twenty minutes of last night’s Champions League match against Braga was a similar affair. Alan handed Braga the perfect start with a header after less than two minutes. It was Braga’s first attack of note and they benefited from poor marking in the Man United box. Eighteen minutes later, Michael Carrick was turned inside out by Eder on the left flank, and a low drive into the box was directed in by Alan once more to make it 2-0.

The second goal seemed to have awoken the giant as Braga’s strict and rigid defending was undone by Van Persie and Kagawa before Hernandez headed home. Normality returned to Old Trafford with that goal, and when the referee blew the whistle to signal full time, the score-line read 3-2 to the home side.

That Man United have trailed in eight of their twelve games this season is no coincidence. There is no single root cause to explain the issue. Rather, it is a combination of factors.

Firstly, defensive errors have riddled United’s start to the season. Last night, Alex Buttner failed to press Alan when he headed in the opener, and then Michael Carrick showed that he is no centre back when he allowed Eder to turn him and cross for Alan with ease. Rio Ferdinand has been labelled as ‘over the hill’ by large sections of the media, a decline that Gareth Bale highlighted when Spurs won at Old Trafford just under a month ago. Patrice Evra has also come in for criticism recently, in that his advancing years is having a dramatic effect on his marauding style and his ability to deal with pacy wingers.

United are also suffering from a lack of options currently available at centre back. Phil Jones and Chris Smalling have been unavailable all season through injury, whilst Nemanja Vidic’s recurring knee injury means it may be some time before he is fully fit. The fact that Smalling and Jones are back in training is a big boost for Ferguson. Smalling in particular seems to have a great chance to stake his claim in the starting XI with the absence of Vidic and the concerns over Ferdinand. Likewise, the versatile Phil Jones can fill in at right back and therefore provide cover for Rafael, though the Brazilian has been United’s most impressive defender this year.

Finally, there seems to be a lack of bite in the midfield. Michael Carrick is the only defensive minded midfielder that Man United possess. Darren Fletcher arguably fits that category, but it will be a while before he is fully ready to influence United’s season.

During the summer, Ferguson bought in Shinji Kagawa in order to revitalise his side’s attack and to pose more of a threat through the middle. Along with Van Persie, Kagawa has been given every chance to cement his place in the first team. This may have come at a cost to United’s defensive balance. The midfield diamond that Ferguson is fielding is much more attack-orientated than his usual formations. His preferred midfield quartet at the moment seems to be Michael Carrick, Tom Cleverley, Shinji Kagawa and Wayne Rooney. Of those four, only Carrick offers midfield cover for the defence. Rooney and Kagawa are obviously attack-minded, whilst Cleverley’s game is centred more around supplying an incisive pass rather than neutralising an opponent’s attack The likes of Anderson and Paul Scholes also lack the defensive nous to protect the backline, so at times the back four are very exposed. The new attacking thrust explains why Man United lead the way in the goalscoring charts so far this year, but it is also the reason why they have conceded a worryingly high number of goals.

Once Ferguson has a fully fit defence to choose from, opposition goals may well dry up. Their attacking might means that a porous defence may not have as big an impact on United’s season as it should, but the manager would be the first to tell you the key to the success of every team he has built at Old Trafford lies in a resolute and unforgiving backline.