What do you base this on?
My experience is that if you are perceived to be good you can get away with being a low performer for a lot longer than if you are not perceived to be good, I have seen it quite a few times.
A false positive would be when a high-performer is perceived as being a low-performer, and terminated for that reason despite their superior productivity.
I can certainly imagine this occurring, especially to employees who are socially deficient, but then you start to get into the quagmire of politically- and socially-motivated terminations, which I think is outside the scope of this discussion.