I have packed into a lot of scrums in my time. I’d say they number in the hundreds. Mostly in the second row, but I’ve muscled up in the front row too, and even, in my youngest days, at number 8 and flanker.

I have packed into scrums that drove the opposition remorselessly backwards, splintering them like a bathroom door in the Overlook Hotel. I have packed into scrums that went skidding backwards like a confused bobsled team, incapable of resisting the other side’s terrifying drive. And I’ve been in scrums that, well, kind of just…stood there, grunting and panting and holding the tension, straining every sinew while wondering why the hell the halfback wouldn’t just pick the frigging ball up so we can get out of this nightmare.

Yes, I have been in many scrums. But if I’m honest, I don’t really understand them at all.

In the old days, there didn’t seem to be much to understand. When I was learning to play rugby, scrums were apparently simple, certainly from a second-rowers’ perspective: you wrapped your arm round tight, got as low as you could, put in a big shove, and then stood up and listened to the coach tell you you weren’t pushing hard enough. If you were in the front row, it was a bit more complicated: you crouched, grappled with your opponent, tried to hold your position, then stood up and listened to the coach tell the second row they weren’t pushing hard enough.

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This simplicity is not in evidence in the modern professional game, and I don’t know whether it’s because scrums have become more complex, or that they always were, but at the level I played nobody bothered much with it – but the fact is, I really do not know how scrums work.

This weekend I will actually be packing into some more scrums, and doing my best to win them, and I still will end the game having no idea how they work. Surely there is no other area in sport, or in life, with such an appearance of being founded on mindless brawn, while actually involving the most bafflingly intricate subtleties.

What I do know is scrums are important. On the weekend, while I ignorantly shove my head in there, the Brumbies will travel to New Zealand to attempt the near-impossible – reaching a Super Rugby final while not being in any legal sense New Zealanders – and we have to be honest: if their scrum performs like it did in the first half of the quarterfinal against the Highlanders, they will be eaten alive.

If the scrum crumples, or starts rollerskating backwards, the penalties will flow, the defence will be in permanent retreat, and the Blues will wash over the Brumbies like an angry tsunami.

And the thing is, I really want to be in a position to give an intelligent take on how they can avoid this. But I can’t. That’s the thing that is both so beautiful and so frustrating about rugby: it’s got so many moving parts and dark arts involved that it can be a labyrinthine task trying to properly diagnose a problem, let alone prescribe a cure.

As far as I can see, each member of a scrum has a specific job. The hooker’s job is hang off the props and strike for the ball in the unlikely event that the halfback puts the ball in the middle. The prop’s job is to try to break the opposing prop’s neck by pulling down violently on his head. Also, there are two kinds of prop, loosehead and tighthead. The loosehead stands on the left and the tighthead on the right, so they need very extensive training to be able to remember which one they are. The locks’ job is to shove the props at each other and develop severe back pain. The No.8’s job is to stand behind the locks and pretend to be pushing. The flanker’s job is to hang off the side waiting for the chance to kick the opposition’s halfback in the legs.

I mean…is that, basically it? The thing about modern scrums, from my perspective, is that the referee plays a much bigger role than he used to. Back in the day, if your scrum was dominant, your reward was that you’d win the ball, be on the front foot, crush your enemies, see them driven before you and hear the lamentations of their women. Your punishment for a weak scrum would be to be repeatedly forced backwards and possibly eventually end up lying scattered on the ground as the opposing pack ploughed through your disintegrating rabble.

These days you don’t see that so much, because the modern scrum, if dominant, is rewarded with penalties, given by referees who carry on them at all times the Big Book O’ Scrum Penalties (foreword by Matt “Superboot” Dunning). Whenever one team’s scrum takes a step forward, the referee closes his eyes, opens the book, waves his finger in the air and pokes at the page, opens his eyes and whatever penalty he’s pointing at, he gives to the team moving forward.

Now I know that this may not be a literal description of how it works, but it might as well be for all that I can understand what the hell is going on. If you can point me towards an authoritative source that can educate me on the details of scrum technique and rules – better than actually being in one ever has – please do. Seriously, unironically, do. I long to understand.

All I know is that if the Brumbies are to have any chance on Saturday – and yes I’m aware that, realistically, they just don’t – that scrum is going to have to stay firm, stay tight, stay upright, not move an inch backwards and never pop their heads awkwardly out the top like seals coming up through an ice sheet for air. If they fail at this, I will not understand what they did wrong, or what they should have done differently, but I know that the referee will stick his arm in the air and the Blues will come down like a wolf on the fold.

So my message to the Brumbies forwards this weekend is simple: whatever it is you’re supposed to do, do that. And whatever it is you’re not supposed to do, don’t do that. I hope that has appropriately stirred your hearts.