Performance cannot be evaluated in a vacuum, and likely has as much to do with your environment as it does your experience and talent. A _high_ performance company, if such a tech company even exists, would do everything in their power not to lose institutional knowledge. Throwing out a low performer is the wrong tact if you have more products and teams then you know what to do with it, it is much better to shuffle that employee into a new environment a couple of times to see if anything sticks.