Wales' points tally matched the biggest Five or Six Nations total Scotland had ever conceded, while the points difference was their greatest margin of defeat in the championship. Johnson's successor Vern Cotter, watching from a distance, must have wondered what sort of shambles he is about to walk into.
Certainly, the first item on his to-do list will be a few quiet words with Stuart Hogg. And possibly some very loud ones as well. The Scotland full-back has shown an excitable streak in the past, but it boiled over into utter madness when he smashed his shoulder into the face of Wales fly-half Dan Biggar after 22 minutes. Referee Jerome Garces whipped out his yellow card, but after looking at the gruesome footage on the Millennium Stadium screens he quickly uprated it to a red.
It was well deserved. As Hogg headed down the tunnel, Biggar rubbed salt in his wounds by clipping a penalty over, but worse was to come. Much worse.
Football teams can gird themselves and get numbers behind the ball when they go a man down, but rugby doesn't work that way. A half-decent team will expect to take advantage of weakened opposition, and Wales are much more than that. It didn't help that Scotland had a debutant wing in Dougie Fife and had already lost captain Kelly Brown with a head knock. It was the perfect storm - and Wales were not slow to realise it.
There was a subdued atmosphere around Cardiff yesterday morning, a collective understanding that this game was the third act on the Six Nations' super Saturday bill.
Yet by its end they were dancing in the Millennium Stadium stands, a red tide of jubilation as compelling as the red tides of Welsh attacks that had washed over Scotland for the preceding hour.
The venom in the Welsh attack exposed a gulf in class between them and their opponents. It had looked bad on paper - the Welsh had more British and Irish Lions on their bench than Scotland had in their starting line-up - but it looked worse still on the pitch. To call it men against boys would understate the extent of Wales' superiority. They tore Scotland to shreds.
They already looked many points better before Hogg walked. The Scots had started at a sprightly pace, churned through the phases to gain field position and, deservedly, three points from Greig Laidlaw's third-minute penalty, but when Wales upped the tempo the difference between the sides was uncomfortably apparent. Biggar levelled the scores with an equalising penalty, and Liam Williams claimed the first Welsh try when he swallow-dived over in the left corner. It was the first creak from the Scottish floodgates.
They would burst just a few minutes later. Hogg became the third Scot in history to be sent off in a Test and public forgiveness might be slow to arrive. It is hard to recall a single incident in the recent history of the sport in which a single rash act had such calamitous consequences.
And so much for the theory that Wales are not the force of the past two years. On top of everything else, Scotland met Wales on the one championship day they chose to play to their stellar potential. Their back row was ruinous, driving the Scots back time and again, and their backline lapped up the spoils with a blitz of pace and scores.
George North - who else? - set them on their merry way 10 minutes after Hogg's departure. On a day when Scotland's open-field kicking had been borderline execrable, Liam Williams plucked another loose kick away from Fife near halfway and set off. Mike Phillips came steaming up in support, then off-loaded cleverly to North. The winger had Dave Denton in front of him, but with one of the easier sidesteps he has executed he cruised in to score.
Biggar's conversion took things along to 20-3, and the only questions left concerned the magnitude of Scotland's imminent defeat. The answers came thick, fast and emphatically.
Jamie Roberts got the third Welsh try just before the break, and North claimed the fourth just after the restart. By now, Scotland's defence was in rabbits-in-headlights mode, and Wales weren't applying the brakes. Before the hour mark, Roberts and Toby Faletau had added the fifth and sixth tries, and a Welsh half-century beckoned.
Scotland did show the resolve to hold them out for a while, but Wales emptied their bench and the fresh legs made a difference, replacements James Hook and Rhodri Williams combining in a kick-and-chase, Williams finishing off. Hook's conversion was just the final nail in the Scottish coffin; their death certificate was signed by Hogg much earlier.