where would such a negative perf come from? And what is that sort of record's nature? Is there any managers here who could clarify how this whole shebang works?
Then there's a semi-annual Perfolympics in March and September, which is peer-review driven (engineers drop everything for about 2 weeks to write reviews) but has all sorts of boondoggles that are easy to abuse. For example, there's unsolicited feedback and even manager-only feedback that you don't see. Google routinely has to pay out settlements because of aftermath of this system. If you work in technology, chances are that you know a couple people who've collected six-figure settlements because of things said about them in the Perf system. Needless to say, this only gives Google further incentive toward secrecy.
Also, Perv really is a "permanent record". A bad Perf will block you from getting promotions and transfers 5 years later.
Google is nothing if not abusive with data, although in this case, I'm hesitant to call that deeply subjective garbage "data".
There is no forced curve. One of your "Perfolympics" is actually optional. Perf is technically a permanent record, but promotion committees will rarely look back beyond one or two cycles (e.g. up to a year). Five years is nonsense.
(I'm another who got dropped into a "poor for me" role. I waited too long to think about transferring. The site director said that I shouldn't have made that mistake. A co-worker on the same team who was in a similar situation at an earlier stage, on my advice, proceeded to begin his transfer immediately. He had a much better experience.)