I recently lost top positions for ultra competitive keyword phrases, yet retained top positions for other phrases. I opened up GG webmaster tools and sorted by organic CTR. I noticed all of my keyword phrases with high CTR held their positions, while those with CTR <10% dropped, and those <4% CTR fell completely out.
Has anyone else observed this? Could GG's new factoring of organic CTR in its Algo explain this drops many have incurred lately?