Rugby is all about manipulating defenders to discover space.

Take that flawlessly executed try up in Scotstoun last Friday. Iain Henderson is sin-binned for flinging Tommy Seymour on the ground so Glasgow have a numerical advantage for a 15th minute scrum just inside Ulster territory.

Rob Herring's heavy heal squirts ball out the back but an instinctive player like Ruan Pienaar can make this work to his advantage. Paddy Jackson is already switching from right to left, coming from the Ulster 10 metre line towards the short side.

Jared Payne is tracking Jackson. Stuart Olding runs the out-to-in decoy line to hold the drift defence.

Fatally, Glasgow outhalf Finn Russell takes two steps forwards that breaks the defensive chain. Entering the land of no return for a defender, Russell has now lost the collision and ends up clinging to Payne’s hip.

The Ireland fullback is running laterally as he strides past Russell but straightens to offer Charles Piutau a one v one with Leonardo Sarto.

Sarto, the 30-cap Italian international, seems to have Piutau trapped between himself and the left touchline. But to compensate for Russell, he’s looking inwards at Payne way too long.

Sarto, flat-footed and reaching with his arms so neutralising his power base, grabs thin air as Piutau accelerates away.

A huge side step embarrasses prospective Lions fullback Stuart Hogg.

As Piutau enters the Glasgow 22 four men are dragged into his orbit.

Untouched, and in his own good time, the offload allows the supporting Pienaar glide further infield.

Eight pair of hands later and Darren Cave dives over in the right corner. Payne has not been idle; he's the penultimate ball carrier, taking seven rapid strides to fix the cover.

This is the sort of decision making that wins tight matches

It’s the type of try Payne and Piutau grew up scoring. So did I. Just not as often.

Where Russell and Sarto fell down was they defended as individuals and not a pair.

Both Sarto and Russell are looking at Jackson to see what he does.

Sarto’s body shape is all wrong so he’s unaware of Piutau’s looming shadow.

A brilliant flash of evasive footwork is still needed to break free but, equally, it highlights the importance of being shown how to defend correctly at an early age.

Now, if I had played all my early rugby at Wexford Wanderers rather than Clongowes Wood I might still have got capped for Ireland. Just nowhere near 83 test matches.

The IRFU are seeking to improve coaching for teenagers across Ireland, in clubs and less traditional rugby areas, to ensure the naturally gifted player is armed with the tools needed to survive later on.

Pienaar probably played some cricket in South Africa but himself and Piutau were so obviously reared with a rugby ball stuffed under their arm. I’ve seen Kilkenny teenagers with that same head-swivelling, awareness of space to compliment their skill-set. Hurlers with thousands of hours pucking sliotars back and forth or against a wall on their own.

We don't have the same volume of rugby players to produce Richie Hogans and TJ Reids. A Luke Fitzgerald comes along every now and again. The Byrne twins. Joey Carbery.

I’ve moved away from the theory that mixing up lots of sport growing up in Ireland is a benefit when it comes to being a professional rugby player. Gaelic games are not really transferable. What are the specific benefits? Catching ball overhead is about it.

Name me the Gaelic footballers who became rugby players? Rob Kearney and Tommy Bowe, not really. Nor was Robbie Henshaw. All good footballers, sure, but those lads were more rugby players who played GAA. Darren Sweetnam is a hurler who, like Tomás O'Leary, has made the switch from Cork underage hurling to Munster.

But it takes years.

I hurled from the age of six to 12. Same time Piutau was learning to ghost past Scottish fullbacks. Give me 20y minutes against a wall and I’ll rediscover my touch. But hurling never really helped my rugby. Took many, many hours away from it, in fact.

Six years of boarding school helped my rugby.

Even shifting from outhalf to wing in December of fourth year slowed my development. It was decided the senior cup team would benefit from turning me into a finisher. That’s three crucial years where I was scoring tries instead of honing the essential skills needed to create them.

I was moved because Bobby Quigley came in at scrumhalf with Ciaran Finane switched to outhalf. Both were quality passers. We reached a final with Bobby and Ciaran as primary decision makers as I was exiled to the back field, where I remained for eight years until an Australian coach figured I was a centre.

Maybe the multi-sports approach or denying natural talent a creative role, with the primary focus being to win above all else, is stunting the growth of Irish rugby.

Then again some things can’t be coached. Hogg will have nightmares about Piutau.

There is a flip side to this argument.

Paddy Jackson is rightly getting plaudits for Ulster’s winning start to the season. He is playing well but not enough to challenge for Johnny Sexton’s Ireland jersey. Not yet anyway.

The best example of this is Johnny orchestrating and creating Josh van der Flier’s second try against the Ospreys on Friday night.

When Johnny is on the field everything goes through him. Arguably too much.

What has Ulster clicking at the moment is the key players who surround Paddy. With Leinster, more often than not, Johnny is first receiver.

Like Rog and Jonny Wilkinson before him, Sexton likes to call the shots for the entire 80 minutes. I can tell you that not too many decisions are made by the inside centre playing alongside these three outhalves.

Whereas for Ulster several players have licence to create. Louis Ludik slots in there regularly and their attacking momentum goes unchecked.

Payne, Stuart Olding, Stu McCloskey, Luke Marshall are all comfortable first receivers and more importantly good distributors. The benefit is the attacking pattern continues if Paddy is clearing a ruck.

There is no right or wrong here but it explains why almost every team seek to take Sexton out with a cheap shot. No other Leinster or Irish player regularly runs the strike moves. Chop off the head mentality.

Rugby is all about creating mismatches and exploiting them.

Manipulating space. Piutau and Payne are experts but Pienaar is the master; an invaluable resource that Irish rugby is about to lose against Ulster’s and Pienaar’s will.

What a shame that a man who wants to stay and raise his family in Belfast, who has embraced the club and driven the culture, cannot be allowed finish his career at Ravenhill.

Ulster are adamant they can afford to keep him. Because he is an priceless commodity; the type of rugby player who coaches merely by togging out for training.

The IRFU see it otherwise. The theory behind denying Pienaar a new contract is unsound. It makes no sense on any level except a point of principle. Ulster will have to recruit another scrumhalf, probably from abroad, to remain competitive next season.

This seems desperately short sighted.

We won’t never see a player with the Springbok’s poise for a very long time. Next season Ulster will have four, maybe five scrumhalves on their books - two are Leinster spares - who have yet to show the requisite abilities to challenge for international honours.

What Pienaar concocted in the 38th minute against Glasgow - literally something from nothing - will be lost.

The Ulster pack is back-pedalling just outside their 22. Pienaar clearly shapes to box kick. Pressure should be on the scrumhalf to clear his lines yet keep the ball in play. Most Irish nines, perhaps all of them, would have blinkers on. One option. Shoulders are parallel, backside facing touchline, the stance of a certain box kick.

With a quick glance over his shoulder Pienaar changes the shape of the game. He wheels around and pops the ball to Cave.

Piutau fends off the hapless Hogg and is away again. This is the sort of decision making that wins tight matches against clubs like Toulon or Saracens.

Let's say a Conor Murray type of player, God knows they are rare on this island, is in the Ulster Academy right now. He is 19 and could be alongside Ruan every day for the next three years. Asking questions.

Why did you do that? How do you kick like that? Why do you always kick to the bottom right hand corner?

That sort of intergenerational knowledge could turn the next Conor Murray into the best scrumhalf in the world. Instead Pienaar will be gone and that teenager will not learn from this technically world class operator.

Next season’s starting Ulster scrumhalf will have to sink or swim.

What if he sinks in Europe? Ulster lose is what.

Worst case scenario is it ruins a scrumhalf who could have had a long career because he gets exposed too soon to a standard he is not ready for.

Getting rid of a guy like Pienaar without a replacement feels like a decision that will prove more detrimental to Irish rugby than its progressive intent.

It also means the time for Ulster to deliver is now. Is their tight five good enough to win a Pro 12? The jury is still out. Rory Best will make a massive difference and Marcell Coetzee's return to fitness might allow Henderson shift from flanker to lock.

But Friday was a serious victory. Winning in Glasgow for the first time lays down a clear marker for the season ahead.

And there was a joy in how they manipulated all those defenders to discover all that space.