There wasn't a sudden increase in rankings - this test showed CTR from Google increased dramatically with the change. When it was rolled out to the entire site, clicks went up, and over many weeks impressions/rankings followed.
but the algorithm also changes, so that could have also been part of it(or your competition made changes), if you dont control all the variables its flawed, IMO. Downvote all you want. I've seen 1000%+ increase without changes, so by that math, could I say that not changing anything at all can increase your CTR by that percentile?