James Shield's Sheffield United Column: This is the biggest mystery in football

Not by the fact it has taken four years to leave the European Union. Or why we continue to entertain the ridiculous theatrics surrounding transfer deadline day.

Rather it is the realisation that professional sportsmen, who according to their managers are perfect physical specimens, seemingly find it impossible to play three times a week.

And not every week either. Just every so often. When teams like Shrewsbury Town begin to get ideas above their station and mess up the Premier League schedule by forcing FA Cup replays.

That is the only conclusion it is possible to draw following Jurgen Klopp’s hissy fit last weekend, having seen Sam Rickett’s side force a draw with Liverpool at the fourth round stage.

Plenty has been written about the competition in recent days, with subjects for discussion ranging from the practical - should matches go straight to penalties rather than being played again? - to the more philosophical: Does the game belong to everyone, or just an elite handful of clubs? (I’m surprised that’s even still up for debate).

But what fascinates me - and, given the huge sums they pay for supposedly cutting edge advice, should concern top-flight chairmen - is the fact footballers now get looked after better than ever. Yet, compared to their predecessors in the Sixties, Seventies, Eighties and even the Nineties, are more fragile.

That is the only conclusion it is possible to draw following recent comments by the likes of Pep Guardiola and Klopp on the matter, with the latter so concerned by the workload being placed upon his squad that, when Town make the return trip to Anfield next month, he is planning to field a reserve team and ask a youth coach to take charge rather than interrupt, for 48 hours or so, Liverpool’s winter break.

Admittedly, it seems ridiculous that fixtures are now being staged during a period supposedly designed for rest, relaxation and all the hi-tec, experiensive pampering which apparently delivers pretty poor results. But that is what happens in a country where the governing body doesn’t actually govern but, following the creation of the PL in particular, is forced to broker half-baked compromises instead.

Klopp also has the right to select whatever eleven he wants. I’m not sure, though, that his refusal to take charge of it affords the opposition the right level of respect; despite being extremely generous towards them before leaving Shropshire.

The German should, however, be commissioning an investigation into why a squad of around 30 or so young men, fine-tuned to within an inch of their lives by a small army of nutritionalists, masseurs, dieticians and assorted therapists, would apparently end-up being consigned to the knackers yard if they are forced to sandwich an outing against League One opposition in between meetings with Southampton and Norwich City.

Six days ago, before Sheffield United’s tie at Millwall, I spent an hour in the company of their former striker Keith Edwards.

I couldn’t help but wonder, after listening to Guardiola’s warnings about the health of top-flight stars, how he coped back in the day; when rehab consisted of a few pints out on the town and the calendar was arguably even more demanding. And the pitches? Well, let’s be polite and say they were a far cry from the perfectly manicured surfaces Manchester City and Liverpool have grown accustomed to performing on.

Yes, the pace of the modern game is faster. Yes, those at the highest level are now bigger and more powerful. But it is all relative after all.

Really, and I’m genuinely being serious, some top-flight coaches need to commission an investigation to why the scientists they employ, experts in disciplines no one had ever even heard of a few years ago, are delivering such poor results that footballers are actually now more brittle than ever.