"Tinderai Chavanga and Jongi Nokwe were also lightning fast.Bryan Habana and Ray Mordt were also lightning fast.
Spot the difference?"
I can see where you're going with this Ceradunce and I'm guessing the answer you're expecting is that the first two failed at test level while the second two were world-class test stars . . . but there's another significant difference and that is Habana and Mordt weren't actually that quick . . . certainly not "lightning fast".
Okay, Habana might have been lightning fast as a youngster but not really after he bulked up so much which is when he scored the majority of his test tries.
Habana relied more on his acceleration over the 1st 10 metres and his excellent reading of the game while Mordt relied pretty much on upper body strength. Neither had particularly impressive top end speed.
Like Habana, Aphiwe Dyantyi is amazingly quick off the mark and gets to his top speed very quickly but that top speed isn't fantastic by international standards.
All goes to show that speed isn't everything . . . even for a winger . . . and along with sheer speedsters like Doug Howlett, Lwazi Mvovo and Jonny May there will always be a place for nippy smaller guys like Habana, Jason Robinson and Shane Williams just as there will always be a place for power wingers like Mordt, George North and Jonah Lomu.
Once in a blue moon you get someone who has it all . . . explosiveness off the mark, exceptional top speed and great power. Rupeni Caucaunibuca was such a player. What a great pity he didn't have more of an international career. Joe Rocokoco in his prime was another. Of the current wingers I reckon Rieko Ioane is probably the closest to being the complete package.
PS When discussing fast wingers I'm excluding some of those insanely fast USA Sevens players like Perry Baker and Carlin Isles.