It seems to me that this particular observation is a fair indication that there is something very massive beyond our cosmic limit of being able to see, that is affecting the way a very large number of galactic clusters are moving. I'm pretty sure the current BB model of our universe is not able to to explain this observation. I do have my own ideas about it, but I'd very much like to know what others think on this subject?
NASA - Mysterious Cosmic 'Dark Flow' Tracked Deeper into Universe