John Barclay, the 43-times-capped openside flanker who has been a Scotland regular for the past six years, and who first figured on the national scene almost a decade ago, is the most high-profile of those who have been left out. The Glasgow scrum-half Henry Pyrgos may also feel mystified by his exclusion, especially as Johnson has named just two other specialist No.9s in the squad.
If form is the issue, then Edinburgh flanker Roddy Grant's omission is staggering. Grant has delivered a series of outstanding displays for his club over the past two months and seemed a shoo-in for promotion to Test level. Glasgow tighthead prop Jon Welsh can also be considered unlucky to be overlooked, especially at a time when Euan Murray has been ruled out by an ankle injury.
Johnson's selection is all the more puzzling as he has given the thumbs-up to players who have been almost inconspicuous this season. The Edinburgh prop Geoff Cross has been named in the party, despite having started just one competitive game while Ross Rennie, Grant's rival for Edinburgh's No.7 shirt, has started only twice.
However, Johnson has also acknowledged the form of one of the most improved players in Scotland this season by including the Edinburgh flanker Dougie Fife as one of just two uncapped players - the other is the Glasgow flanker Chris Fusaro - in the training party which will meet up at Murrayfield after this weekend's Heineken Cup games.
In the absence of the injured Tim Visser, Fife, 23, has emerged as Edinburgh's main attacking threat behind the scrum this season. He has scored five tries in seven games, the most recent of them coming against Perpignan last Sunday.