This is a time of hope for fans, like Christmas morning, when the club they support just might seal a deal that will change their destiny. Of course, it rarely works out like that, but allegiance is all about submitting to unrealistic expectations.

However, it is also a day with unpleasant echoes of the meat market, in which human beings can be bartered like gambling chips and a price put on anyone’s head. A day which makes plain the professional footballer’s mercenary status and the insecurity players endure in exchange for a shot at substantial wealth and the adulation of millions.

What is often not appreciated is the key role this seemingly archaic sports bazaar has in helping an industry which has more trouble controlling its costs than almost any other I can think of get anywhere close to balancing its books.

It can do this in part because of the asymmetry in the way that transfers in and transfers out are accounted for.

First of all, players are not players for the bean counters: they are "intangible assets."

The value of these intangible assets in the books of the biggest clubs sometimes dwarfs that of tangible assets, such as stadia. The balance sheet of Chelsea Football Club Limited as at end-June 2021 shows £432 million ($581 million/€518 million) worth of intangibles against £140 million ($188 million/€168 million) of tangible assets.

More importantly for the purposes of this piece, the rules make it theoretically possible for a club to sign four players for £20 million ($26.9 million/€24 million) each, £80 million ($107.6 million/€96 million) in total, offload one, also for £20 million, and yet record an overall positive impact on that year’s profits.

How? Because when clubs buy, they are usually allowed to spread, or "amortise", the cost of the acquired player over the length of his or her contract, frequently five years.

If the four notional players in our example are indeed given contracts of five years’ duration, the £80 million aggregate cost could be spread equally over that time-frame, giving a figure of £16 million ($21.5 million/€19.2 million) a year for five years.

When clubs sell players, however, they are normally permitted to book the entire associated profit immediately.

This does not automatically mean that the sale of any £20 million player will yield a profit of the same amount in that year’s accounts. The exact amount will depend on the employee’s book value at the time of the transaction.

This book value, in turn, has nothing to do with any attempt to assess the player’s actual market value at a given point in time; it derives from a simple financial equation.

If the offloaded player is a product of the selling club’s youth system, like say Liverpool’s Trent Alexander-Arnold, his assigned book value for accounting purposes will be zero.

In reality, Alexander-Arnold would be worth tens of millions of pounds if the Merseyside club decided to sell him. The website Transfermarkt assessed his value at £72 million ($97 million/€86 million) in late December.

If one of these so-called "home-grown" players is sold for £20 million, then a profit of the same amount can generally be included in that year’s financial results.

In the event that the offloaded player has previously been purchased, however, then any profit on the deal will depend on that price tag and the proportion of the employee’s contract that remains to run on the date of his disposal.

A player who costs £20 million and is subsequently sold on half-way through a five-year contract would have a residual book value of half the original fee, ie £10 million ($13.5 million/€12 million).

So if the club he represents sold him at that point for £15 million ($20.2 million/€18 million), they should normally be able to record a profit of £5 million ($6.7 million/€6 million) when you might intuitively expect a £5 million loss.

This all helps to explain why very often, clubs announce - correctly - that they have made a profit on player transfers during a given financial period, despite paying out far more cash for new signings than they have recouped from those they have themselves sold on.

Yes, club football exudes an image of almost fantastical wealth at the elite end of the game, particularly nowadays, given the huge riches associated with many owners - yet the perennial cost-control issue means that things can quickly go pear-shaped, especially if something wholly unexpected, such as the continuing COVID-19 pandemic, emerges.

Ah, the beautiful game, eh?