Your personal experience notwithstanding, I don't think that it can be generalized that there is always an under-performer on every team.
If I may offer my anecdata, I've seen several teams that could be characterized by stability and depth of expertise in their respective areas. You could say they always performed on a very high level, but never over-perform, because the high level is what is expected. Stack ranking those teams equates to killing them.
I also agree that a scenario where all individuals over-perform all the time is also rather unrealistic. But individual evaluation of performance is not stack ranking.
It depends how big a “team” you consider. At the 5-10 level maybe not. At the 30-50 level most likely yes. At the 100+ level there are certainly a few.
In the well run orgs at Amazon the bell curve is applied at the larger scales where it makes sense.
I would use different terms for such organizational units (group, department, division), team, in my mind and use of language, would mean low two-digit (at most) number of people reporting to the same manager and collaborating on similar topics.
But sure, the larger the structures the more likely regression toward the mean will kick in.
If I may offer my anecdata, I've seen several teams that could be characterized by stability and depth of expertise in their respective areas. You could say they always performed on a very high level, but never over-perform, because the high level is what is expected. Stack ranking those teams equates to killing them.
I also agree that a scenario where all individuals over-perform all the time is also rather unrealistic. But individual evaluation of performance is not stack ranking.