When Hogg smashed his shoulder into Biggar's jaw he gift wrapped victory for Wales, and the only question from that point on was how many points they would score. The answer was a brutal rebuke for the Scotland full-back's moment of ill-discipline.
So, to the consequences. Scotland had been reasonably competitive before Hogg's dismissal in the 22nd minute sent them reeling into disarray, and they could still legitimately have entertained hopes of stealing their first win in Cardiff in 12 years. Had they racked up a decent score they might even have snatched third place in the championship table. The difference in prize money between that and fifth is close to £1m pounds. Just as well that Hogg hammered out his new contract a while ago.
Hogg is as robust as he is feisty and he will recover from the ignominy in due time. Coaches and fellow players lined up to say that his action was out of character, but they should rein in their sympathy before it gets out of hand. Frankly, what he did is the kind of thing of which you should feel ashamed.
Yet Hogg's usefulness as a scapegoat should blind nobody to the wider weaknesses of Scotland, the team and the rugby nation. As Wales ran riot, amassing a points total and a winning margin that measured a record Scottish defeat, they did so with a swagger that has been entirely absent from Scotland's performances in recent years. You would have to go back to the last century to find a Scottish performance as fired by confidence as Wales were in Cardiff on Saturday.
While Hogg's departure almost guaranteed that Scotland would lose, it was far from inevitable that they would be hammered as badly as this. When Wales lost their captain, Sam Warburton - he is far more a talisman to his side than Hogg has ever been to Scotland - after 20 minutes of their 2011 World Cup semi-final against France, they went on to lose by a single point, 9-8, and were still fighting at the finish. The fight went out of Scotland too easily here.
As he admitted, it was not the way the interim coach Scott Johnson wanted to end his time in charge before passing the baton, or maybe the poisoned chalice, to the incoming Vern Cotter. Johnson was rightly panned for his flippant attitude after last month's feeble loss to England, but it would have been harsh to tear strips off him for having a certain lightness in his step on Saturday evening. Had he waggled a cigar and issued a cheery "That's all, folks", his inner relief would not have been clearer.
Or is it a case of 'goodbye frying pan, hello fire'? Having relinquished command of a misfiring Scottish team, Johnson now assumes responsibility for a misfiring Scottish system. He has breezed his way through the past 15 months with the consistent message that the Scotland Test side is a work in progress, but the reality is that the material has needed a lot of work, without much solid evidence of progress.
Johnson said: "The way I look at it is that, in the past year, we have capped just about a full contingent of Scottish internationals. We are trying to build on this base because we have an arduous 24 months, with a lot of demands.
"I'm pretty happy with where they are going. They are getting runs on the board. You don't see it just yet, but some of these players are going to be stand-out players. I'm happy with the fact they can compete athletically. That's what I like.
"We will always be exposed to injuries, so I wanted to make sure that we did the hard yards now. I wasn't going to run away from it. I keep saying it would be easier to sit back and do the tried and tested, but if we got a bump or two then we would have felt we were in trouble."
There are a couple of significant flaws in Johnson's argument. If someone is not good enough to be a Test player then he is not going to be turned into one by the addition of a little international experience.
Over the course of last summer's tour to South Africa, the November series and the RBS 6 Nations just ended - 11 games - Johnson used the staggering total of 46 players. In his 15 months in charge he saw fit to give debuts to 16. It is all very well widening the pool, but it can be pretty shallow in the margins.
The contrast with Wales is glaring. In their dark years, through the eighties and nineties, handing out caps like confetti was a sign of Welsh desperation rather than Welsh squad development. Players were capped and ditched in the blink of an eye. Why on earth should we believe that Johnson is doing anything different when every Tom, Dick and Harry in Scottish rugby - and beyond - now has a framed shirt on his wall?
Another contrast is rather more enlightening. The Welsh threequarter line, Lions all, boasted a total of 161 caps, a touch more than 40 per man. Their Scottish opponents were not exactly ingenues, but it was fascinating to note the ages at which the respective players made their debuts. For Wales, Jonathan Davies, Jamie Roberts and Alex Cuthbert were all 21 when they first entered the international arena, while George North was just 18. Spot the difference with Scotland, whose debut ages were 23 (Dougie Fife and Alex Dunbar), 21 (Matt Scott) and 25 (Max Evans).
Clearly, the Welsh have a production line that Scotland cannot match. But then, the Welsh have four professional teams, a thriving Premiership and an efficient age-grade structure. Scotland lags in every area.
If Johnson is to concentrate on one area above all others when he assumes the role of director of rugby, it should be the nonsense of young players being denied meaningful competitive rugby between the ages of 16 and 20. Because the longer we stick with the status quo, and the longer we allow entrenched interests to continue to have things their way, the more familiar results like this one will be.
Make no mistake, this was a slaughter of the innocents, although Hogg can probably be counted a dishonourable exception from that category.