Google has this little thing it does. Its called first priority.
It means things near the beginning of something has more influence on that particular thing than the one near the end.
So the begining of a title has more influence on the focus than the end. Same thing with paragraphs, sentences, blocks of text, location of text on a page, even the first link on a page is more powerful than links further down the page.
I explain it to my students this way:
There are three ways to use a title for a small businesses.
To emphasize the brand name of the business
To emphasize the service or keyword
To emphasize the location of the business.
Lets suppose your customer is "Larry's Transmission Service", that the keyword that you are targeting is "affordable transmission repair" and the business is located in Chicago.
This is a typical title emphasizing the keyword first, the location second, and the Brand last.
"Affordable transmission repair - Chicago - Larrys Transmission Service"
If you wanted to emphasize the location first then the keyword, you would do something like this:
"For Chicago's most affordable transmission repair, call Larry's"
If if the businesses' brand name receives search volume, you may decide to emphasize this brand name first on some pages.
For instance
"Larry's transmission service, affordable transmission repair - Chicago" (brand first, keyword second, location last)
or
"Larry's transmission service, Chicago - Affordable Transmission repair" (brand first, location next, keyword last)
What you did when you wrote the original title was tell the search engines that "A" was more important than "B", and "B" was more important than "C". Since the single most powerful part of on page SEO is the title, it has a huge influence on the ranking of the page. (which is why each title needs to be unique to that page, not the same title on every page of the site)
So Google ranked your page accordingly.
Then you went in and changed the importance by shifting the words around, and telling the search engines that "C" was more important that "A".
So google re-ranked your site with this new info.
Now add to this that Google bounces site ranking all the time. If you see a fall in rankings today, you should not react to it. You should watch it. It might be a glitch.
It is possible that yor site was on a honeymoon, and the real ranking kicked in about the time you made the change, allowing you to add 2 + 2 and come up with 6000.
It is possible that your site was ranking and incurred a penalty from link-building.