Seems to me that the new Google Interface became universal on May 5 [googleblog.blogspot.com], Cinqo de Mayo. The algo changes hit heavily on May 1, Mayday.
So you've got a 5 day period of algo effects before the interface effects kicked in. It's not a lot of time, but it's what we've got to sort out the difference between the two.
So when did traffic changes first kick in for you? If it was May 1, you're in the wrong thread. This thread's discussion is about Google traffic changes beginning on May 5, when the new layout kicked in.