It's weird to think that Sampras was just one Krajicek away from doing the same thing at Wimbledon.
He didn't though. You could say Nadal was one Soderling win away from having won RG 7 in a row - a much more physically demanding slam and one with far more specialists on the surface than on grass.
Same for Fed - he could have won US Open 09 and maybe even 10 - he was very close. He'd have had 7 in a row there.
The reason the 8 is so impressive is precisely because he's not had one bad day - and to me it's tougher in a best of 3 in some ways as it's easier to be upset by a hot opponent. If you're as great as Sampras was at Wimby or Nadal at RG then it's more of an achievement to beat you there than in a best of 3 event on grass/clay - the fact that Nadal hasn't lost 2 sets in a match at MC over 8 years is astounding. He's not even been close to losing. Been taken to a deciding set 4 times and won that 6-1 three times I think. The closest was Gasquet in 2005 (6-3/6-4 in the final set I think....).
It's a perfect match of man and surface. Since 2007 he's lost 2 sets - one to Djokovic, another to Murray.
It's not about saying that 5 Wimbledons or 5 US Opens in a row aren't impressive - they are. But winning 8 in a row of anything, in any sport is nigh on impossible.