Hardly relevant. Tennis is played against the field, not against three players, and Nole has been the best player of the year overall. Not to mention this 'since Mid June' streak is only 5 matches.
On the other hand, it says a lot about his consistency that he hasn't lost to a non-Big 4 member since May, and only twice this year.
But it is a bit of a concern. He wouldn't want to be a best of the rest style of player....
Three times: Isner in Indian Wells, Tipsy in Madrid, Delpo in Olympics.
And he wants to be a best in the world style of players, which he has clearly been in 2012.