There was no excuse about playing one of the world's top two sides; no excuse about not getting enough help from the referee; no excuse about not having enough possession; no excuse about lack of opportunities; no excuse about not having sufficiently good support; no excuses about the venue; no excuses about not having his own management team in place.

No, there was no excuse of any sort for Andy Robinson's side losing to the world's 12th-ranked team – who represent fewer than 105,000 people spread over 52 islands in a South Sea archipelago – in a provincial Scottish city boasting more than double that population.

On Saturday evening, once the head coach had acknowledged that there would be "consequences", it was hard to see what he could possibly mean other than he knew he had to go. As uninspired as it was uninspiring, Scotland failed to score a try for the 18th time in Robinson's 35 matches and, while they have claimed some remarkable backs-to-the-wall wins, they were deservedly beaten at Pittodrie.

Poor Tom Heathcote, whose qualification for Scotland emerged through him being a team-mate of the head coach's son in England's under-18s, was the last of many who were culpable when his knock-on ended the game. However, to apportion blame to the 20-year-old would be as ridiculous as it would be unfair.

That, allied to his failure to level the scores with a penalty not long after being sent on to the pitch to ensure that he was tied to Scotland, will be seen to vindicate some views that he should not have been playing without serving his time or proving himself among the squad. Yes, Heathcote's involvement was a bad decision, not for those reasons but because so much responsibility should not have been placed on the shoulders, hands and feet of someone who has not this season played a top-flight match.

That, though, is merely the latest reason to question Robinson's decision making. More pertinent, perhaps, is the deeper malaise within Scottish rugby, specifically, and Scottish sport in general. The talent is just not good enough, as was exposed by these wildly indisciplined but explosively gifted opponents.

The former was exposed by the fact Scotland had the opportunity to play against 13 men at one stage and against 14 on three other occasions, including the final few moments when they were unable to capitalise on set-piece opportunities five metres from the Tongan line. That deficiency was made all the more glaring by Fetu'u Vainikolo, whose turbo-boosted break registered the second visiting try, and by the man who got away from Glasgow Warriors, Viliami Ma'afu. The No.8 was handed the man-of-the-match award in view of his excellent work in the build-up to both of his side's tries.

Perhaps the performance that completely summed them up, though, was that of Tukulua Lokotui, the first of the trio to be shown a yellow card but also the first to register a try as his 6ft 5in, 17st 9lb frame overpowered wee Greig Laidlaw at point-blank range. Laidlaw, it should be said, kept his team-mates in it until the closing stages, having registered all of Scotland's points.

What had to be the biggest consideration for Robinson in leaving, however, is that Tonga were not only superior in their individual attributes but they were also collectively more effective at the game's key moments than a much better-resourced nation. That raises serious questions about the capacity for improvement within the current set-up. Rugby is a technical sport, which is why the Tongans' Fijian neighbours have so rarely managed to turn their extraordinary skills into anything terribly useful in the full 15-a-side version of the game.

If it is understandable that Scotland were outplayed by the New Zealanders, whose culture dictates almost every boy in the country aspires to be an All Black, and outmuscled by South Africa, where manhood is measured in mauling and scrummaging ability. They should still have organisational superiority over the likes of Tonga.

That was demonstrated on Saturday by first-half possession and territory statistics of 73% in Scotland's favour, despite some awful handling and the failure to get the ball down after mauling over the Tongan line.

When clear chances were created, Al Strokosch's inability to link a three-man overlap and a failure to get the ball to Max Evans and Tim Visser on the other flank after a superb Sean Lamont charge down the right spoke to a lack of skill and composure. That they led only 6-3 left them vulnerable and the Tongans, despite initially slipping further behind, seized their first opportunity as Lokotui powered over.

Still, the Scots had more than enough of the game to again take charge of the contest, but could only nudge themselves in the right direction with Laidlaw's fourth and fifth penalties before Fangatapu Apikotoa made it a two-point game with his third strike from five attempts. Then came another telling Ma'afu surge, which created the opportunity for Vainikolo to be sent searing triumphantly away for the decisive score.

The closing stages were a shambles as Tongan indiscipline presented Scotland with a string of opportunities to save the day and perhaps their coach's career. Yet the way the ball was fumbled between Kelly Brown and Rory Lawson, two of Robinson's six captains, at the last scrum was as symbolic as Heathcote's final touch in terms of why it all went wrong for this regime.