Edward Gibbon’s magisterial The History of the Decline and Fall of the Roman Empire teaches that Empires crumble from within as much as they succumb to external threats. While Gibbon pointed to the outsourcing, decadence and increasing ‘effeminacy’ of the Romans as key to their eventual capitulation, in the case of Sir Alex Ferguson’s once all-conquering Manchester United, the internal erosion in recent years has been a touch more literal.

Since Roy Keane left for Celtic in 2005, the Red Devils have lacked a truly tigerish midfield enforcer, and with Ryan Giggs and Paul Scholes slowly succumbing to age, unable to cover for the frequently indifferent form of Anderson and Michael Carrick (or Darren Fletcher’s bad luck with illness), the middle of the pitch has been the centre of much of, if not a classic fall from grace, then a definite sharing of the podium with Chelsea and their oil-rich neighbours.

However, the crack in what was once the foundation of a formidable side has spread, with the central defensive options increasingly shaky – Rio Ferdinand and Nemanja Vidic have spent much of the last few seasons injured, as have their various understudies, and consequently Old Trafford is far from the intimidating, impregnable fortress of a few seasons ago, let alone its golden age. The goalkeepers are also hardly as imposing as the legends of Peter Schmeichel or Edwin van der Sar, mere princelings in comparison to those match-saving kings.

It could even be argued (at a slight stretch, admittedly) that even their formerly illustrious line of centre forwards is not quite as awe-inspiring as before. Robin van Persie may have joined Wayne Rooney to make one the most lethal front pairings possible in the Premier League, but so far they haven’t been used much in such a way – and would the quartet of Rooney, Van Persie, Danny Welbeck and Javier Hernandez really compare favourably to the European Cup-winning Rooney, Cristiano Ronaldo, Carlos Tevez axis of 2007-09 or Dwight Yorke, Andy Cole, Teddy Sheringham, Ole Gunnar Solskjaer of the 1999 Treble? Do the options on the bench have the same match-winning magic of old?

The nature of this weakness at Manchester United’s core has been known for some time – there were symptoms and scares before Barcelona bulldozed through the bandaged middle in the 2009 Champions League final, and since then it has only become easier to play through the gaping holes. Swiss outfit Basel bested Manchester United with nimble footwork, while Newcastle United’s Yohan Cabaye and Cheik Tiote dominated the 3-0 victory last season so much it recalled the regal nature of Scholes and Keane’s halcyon days.

With even mediocre sides enjoying the freedom of Old Trafford, the time had come for Ferguson to find a solution – and the Scot has not managed one of Europe’s biggest clubs for more than a quarter of a century without cunning, creativity and a canny knack for knowing when to move with the times.

And, in an almost unprecedented manoeuvre, he has set up his side without two orthodox wingers, instead loading the middle of the pitch. The last two matches against CFR Cluj and Newcastle, saw Ferguson deploy a narrow midfield three of Carrick, Tom Cleverley and Shinji Kagawa, with Rooney in the hole behind Van Persie and Welbeck. The intention was clear – firm up the soggy middle with as many bodies as possible – and it worked, Cluj comfortably overcome 2-1 in Romania and the Magpies coolly disposed of 3-0 at the scene of one of the last campaign’s lowest ebbs.

It hardly counts as a unique tactical gambit, resembling Carlo Ancelotti’s AC Milan in its compact midfield supported by a floating fantasista and two strikers, but for a manager who has normally only tinkered with his favoured set-up – sometimes deploying a 4-5-1 or 4-2-3-1, occasionally playing the wingers higher up in a 4-3-3 – to see Ferguson sacrifice the territory out wide was certainly against type. However, with the quality so patently lacking at present, the only solution for firming up the soggy middle was quantity – and until the opportunity comes in January to procure some central reinforcements, this may be the shape of things to come.

This tactical reorganisation may have succeeded in staving off the threat of embarrassing reverses in relatively minor border skirmishes, but there are bigger and uglier barbarians at the gates moving to sack the citadel.

Manchester United may have buttressed their buffeted centre, but the side still misses a true ball-winner in the manner of Gennaro Gattuso or Javier Mascherano, which could cost them against more effervescent sides like Chelsea, Manchester City or Barcelona – as beautiful with the ball as Kagawa, Cleverley and Carrick may be, unless they learn to be beastly in winning it back it could ultimately prove to be a futile effort to reverse the tide. The loss of Paul Pogba to Juventus was keenly felt, with few possible alternatives currently on the books, and having been priced out of a move for Javi Martinez the other options range from raw to overpriced or overrated.

With one of the game’s greatest generals still barking out the orders and able to outlast all his challengers so far, it would be premature to herald the end of days at Old Trafford just yet. The looming battles with the bigger sides will prove whether or not football really is witnessing the decline and fall of Sir Alex Ferguson’s Manchester United Empire – contests which the Gibbons of football’s future will judge.