Yea, I think I recall seeing this a couple times before - was pretty sure it was just a bug and possibly had to do with SAB's and hidden addresses. But that was just a pretty quick assumption at the time.
Things could definitely be a bit more buggy with all the local updates going on.
I might be able to shed some sort of light on this matter. Recently I too was seeing a lot of service area businesses rank higher and this is what I found on almost every single case that i looked into.. Since the new pigeon update Google has a huge fluctuation on service base businesses mainly if you look closely all locations even the ones with no address showing ALL have a lot of followers on there social pages or Google Plus local Pages...
Also the service base businesses that outrank have more reviews usually sometimes this is not the case but 9 out of ten I have looked at it was..
Judging and looking at more similar service base businesses it became a pattern that social media and being active on your Google My business page such as posting each day with something geared towards your business would increase your ranking with in Google.. A ranking Factor I think so I know for a fact and have tested this with many colleges even that click through rate is a HUGE factor Post Pigeon update.
Click through rate in a lot of tests even moved some of the locations more than 2 to 3 positions higher.
But it is still early to actually see what Google has planned with result fluctuating like they have been pulling from new data centers one day then old the next.
It is making it very hard for us to catch that pesky Pigeon Bird!!
I at times feel like Sylvester the cat trying to catch twenty!! DARN YOU GOOGLE!! lol
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