With Manchester City’s £25million signing of Wilfried Bony now complete, the transfer window is finally beginning to excite as we head into the month’s 15th day. Many expected Manchester United to be up there with the busiest of teams this month. However, as yet, Louis van Gaal’s side have added just one player to their squad — 32-year-old free-agent goalkeeper Victor Valdes following the Spaniard’s rehabilitation spell with the club.

With just half of the January transfer window left, time is running out for United to make significant additions with the mid-season window having long been known as a period not exactly conducive to sensible negotiations particularly where elite players are concerned.

Irrespective of this, United’s performances so far this season have shown a vast improvement on the 2013-14 campaign, despite what certain statistics would have you believe, although the club is still a couple of signings away from being able to operate at a consistently high level.

The club have acknowledged that defensively there needs to be an improvement. This was clear in the summer following the departures of stalwarts Rio Ferdinand and Nemanja Vidic with no replacements being found for either.

Marcos Rojo has come in from Sporting Lisbon and impressed. However the trio of Jonny Evans, Chris Smalling and Phil Jones have all struggled with fitness and injuries, which has made their transition into Van Gaal’s system difficult. It is believed that Van Gaal remains unconvinced by all three, as told by the Guardian’s Jamie Jackson and that a defensive signing is his priority this month.

Van Gaal’s first-choice target in this area remains Mats Hummels. The graceful center-half is in the prime of his career having just won a World Cup and been named Dortmund’s club captain aged just 26. However, with Dortmund’s faltering domestic form and United’s obvious allure, there is every chance this is a deal that could happen, although it is unlikely to be this month.

Having said that, Borussia Dortmund would be creating a catastrophically troubling situation for themselves if Hummels was allowed to leave in January.

For supporters, seeing their club in the relegation zone halfway through the season is painful enough but if the acrimonious departure of their captain was piled on top of that, the club would have a lot of very difficult and possibly quite discourteous questions to answer.

Aymeric Laporte and Raphael Varane are other possible targets with the two Frenchman believed to be on United’s radar. Varane recently signed a contract extension with Madrid in September yet rhetoric around his future continues with neither party seeming to be on the same page.

At just 21-years-old, Varane would be the perfect long-term addition to United’s defensive line, even more so when you consider Varane’s performances for Madrid have often just teetered around what you would expect from an experienced, world class defender.

Laporte would seem the most likely January arrival. However Athletic Club’s business model would put paid to any possible deal.  Laporte’s buy-out clause was increased to 42million euros last summer, which roughly translates to £32million. Athletic are in a position where their hand can’t be forced, Laporte is under contract until 2018 and the club will reject any offer forcing a buying club to meet the player’s buy-out clause, thus giving the Basque giants a level of innocence in the eyes of their supporters.

Given United’s rumored interest in Mats Hummels is at a similar price according to the Mirror’s David McDonnell, it seems unlikely the club will part with the same figure for a defender aged just 20 with the club needing a figure of leadership at the back.

Whilst center-defense is United’s priority this month, there is also a desire on Van Gaal’s part to recruit a central midfielder and a right-back, neither of which being as important this month as a central defender.

Kevin Strootman continues to be Van Gaal’s primary target for midfield with the Dutchman showing everyone just what he is still capable of following his knee injury in the recent Rome derby against Lazio. Roma again are under no pressure to sell and it is unlikely a deal will be struck this window, although Van Gaal is believed to be determined to test Roma’s resolve on this matter.

United’s midfield has impressed in parts this season with Marouane Fellaini’s return to the side coinciding with the club’s 10-match unbeaten run. The Belgian has been excellent in utilizing his best attributes. However there is still a lack of leadership in midfield which sees United struggle when matches begin to run away from them.

The right-back issue is a contentious one amongst supporters with half believing Rafael is capable of claiming the starting spot and the other half disgruntled with the Brazilian’s lack of defensive nous and inability to stay fit for long periods of a season. It seems Van Gaal is a member of the latter camp with Seamus Coleman, Nathaniel Clyne and Dani Alves all being reported as United targets.

At present, it would be fair to say the pressing concern for United is the center of defense. If there is one position where not buying a player this month could cost the club a top four finish, it is there. There is no confidence amongst United’s defenders at the moment and as a result the rest of the team appears at times awkward and unsure whether they can truly attack with freedom.

United’s best football has come using the 4-4-2 diamond this year. However, the lack of defensive protection it provided caused United real problems. The perfect scenario for Louis van Gaal would be to sign Mats Hummels this month and return to the diamond system.

Whilst that is unlikely, it is certain that the Dutchman will try and sign a defender this month and it appears to have got to a point where United’s season may very well depend on it.