Manchester United endured a nightmare campaign under David Moyes last term, as the club finished the Premier League season in seventh place.
There were many things wrong with the Red Devils under the previous regime, with the club struggling to find an identity. And, for some time now, it has been clear that the Red Devils are lacking in the middle of the park, but it's not just the midfield area where the club are struggling.
As well as midfield, United struggled defensively under Moyes. In the club's 19 home league matches last term, they conceded 21 goals in their own back yard - four more than Stoke City and three more than relegated Norwich City. The likes of Arsenal and Chelsea, who managed to secure Champions League football, conceded just 11 goals each on their own stomping ground.
Perhaps Manchester United's best defensive display under the previous regime was against German giants Bayern Munich in the quarter final of the competition. On that night, the club secured a 1-1 draw at Old Trafford with the Bavarians, as United finally gave fans a performance to be proud of.
However, against Bayern, United's defence looked like this: Phil Jones, Rio Ferdinand, Nemanja Vidic and Alex Buttner. The latter three have now all departed the club and, on that night, Jones wasn't played in his preferred position of central-defence.
And, despite Jones' solid performance on that evening, the England international has struggled at the Theatre of Dreams in recent time. In 2012/13, Sir Alex Ferguson suggested that Jones could become the club's greatest ever player. Jones' career has stood still since then. The former Blackburn Rovers man is still just 22-years-old, but he's struggling to find his feet at United.
Smalling and Evans
And, as it stands, Jones will only have two main rivals for the centre-half positions next term. Chris Smalling and Jonny Evans will be out to make a name for themselves under Van Gaal, but United fans may well be worried.
Smalling, much like Jones, hasn't been able to hold down a place in United's back-line in recent time, and has struggled for form and consistency. Evans, on the other hand, enjoyed a fine season as United won the Premier League table in 2012/13, but injuries slowed down his progression last term.
And, despite Evans' sold form in Ferguson's last season in charge, some Manchester United fans remain unconvinced. So, then, as Van Gaal is set to take over on a permanent basis, can he trust his three central-defenders?
Well, in truth, he can't. The trio haven't been able to show their credentials on a consistent basis over the last couple of years at United, meaning they could prove liabilities for the club under the new regime.
Additionally, a lack of experience could cost the Red Devils in 2014/15, in what may well prove to be a crucial season for the club. If Manchester United go another season without Champions League football, then they could end up in the wilderness. Van Gaal must make it a priority to improve his options at the back or face a defensive nightmare next season.
United fans will be desperate for the likes of Smalling and Jones to step up next season, but they've just not done enough in recent time to prove they can cut it at the top. If Van Gaal doesn't add defensively, then he will be taking a huge gamble. Jones and Smalling can still be the future of United, but they may need some help next season.