Manchester United have taken their spending to 50m in the close season as David De Gea flew in today to undergo his medical, making him the third player to be signed in this transfer window by the 19-time English champions.

De Gea joins Phil Jones and Ashley Young in infusing the United squad with youth and talent, as Ferguson finally calls time on his ageing group of stalwarts and belatedly overhauls the squad.

However, De Gea was more or less expected since May, Young was confirmed at the start of June and Jones is hardly the signing to set the United fans’ pulses racing. While the goalkeeping position was the most crucial one to fill, these three signings don’t hide the fact that Manchester United are still on the lookout for one or two central midfielders, and that their spending could go well beyond £50m (although player sales should alleviate some of the burden) if the manager brings in reinforcements.

For a side that has won four league titles in five years, it’s astonishing to note that they have played with a patched-up midfield for nearly 8 years now. In this time there have been moments of midfield dominance – Carrick’s performances in 06/07 or Hargreaves’ brief cameo in 07/08, but mostly the results have been built up despite a shaky midfield unit and quite often by bypassing the midfield completely.

Hargreaves and Scholes are gone, Gibson is likely to follow them out. Anderson is yet to improve mentally, while Fletcher, on his best of days, is a more-than-capable backup midfielder. That leaves United with Carrick as the senior recognised midfielder, with Giggs and maybe 1-2 youngsters from the Reserves / U18 teams considered good enough to make the United midfield next season.

It’s an old problem – United play a fluid system that interchanges between 4-4-2 / 4-5-1 / 4-3-3 depending on the circumstances, and while they have the strikers and wide players to spread out or tuck in, step up or go deep to get the ball, they don’t have the midfielders to cope with the demands of either systems. Most crucially, they don’t have a capable foil for Carrick.

Too many players at United are good at multiple roles but not good enough specialists. This is felt most keenly in central midfield, where you don’t have a very good defensive midfielder (Carrick can only ‘do it’ in a two-man holding midfield) or an exceptionally talented advanced playmaker (Carrick isn’t quick enough to play there on a regular basis). The most obvious solution would be to bring in four new players and ship out the current stock but this isn’t fantasy football or football manager, and therefore Ferguson has to make do with his current resources.

That means bringing in an experienced midfielder with a specific role to build the midfield around, or to bite the bullet, trust in Carrick and build it around him while bringing in a youngster (again a specialist). There are some good targets – not your Sneijders and Pastores – but younger players in the mold of Moussa Sissoko, a hugely talented prospect who can mix defensive and offensive responsibilities in central midfield a la Michael Essien. Or you could take your pick from half-a-dozen standout youngsters from the recently concluded U-21 European Championships (although one feels that if United were going to buy from there, they would have done it earlier in the season).

The transfer window opens this Friday, and we’ll have two whole months of intense transfer speculation. Players are most likely to go, but all eyes will be on the midfielder United sign. Or don’t sign, as the case might be.