I'd say Larry Page set the seeds for this when he was CEO for the second time and chose Sundar to be his successor while also forcing the company into a disastrous social platform when they should have focused on cloud while shutting down all the fantasy projects. Larry picked Sundar because he was a consolidator who got the other execs to stop fighting and was smart enough to know how to "grow" google's market share over the next decade (which he did). But that growth came at the expense of most of the things that made google great, and now that the profits aren't growing rapidly any more, all the stuff that was fun simply because there was a lot of money floating around are gone.
For me, it it began to end when a director stole my project from me and forced me out, then bad-talked me at perf calibration, and finally ended when I realized my new management was just "night school MBAs with a little bit of technical knowledge and no management skills other than ass kissing the VP".