One thing I've seen "performance" is largely subjective. It is not just X cls or Y design docs (and you can see how these artifacts are easily gameable). A large part is visibility, likeability and awareness of org politics. A lot of them are maximizing personal gain over company gains. As a reasonably well-performing manager and former IC (as well as getting my share of not so great ratings) this was the game I hated but accepted to play - after many years of denial. And don't worry, companies know this. Check out Macleod's hierarchy or Man in the high castle!

So if you are worried that "top" talent will leave don't. Their departure is not damaging the company as much as the boat remaining unrocked!