Thinking it through, I think Gigabet's theory is correct, and experience leads any thinking player to similar ideas.
What does it mean, practically? Among other things, if you have a 1.3K stack at t150, BB has 1800 and the median is about 1.2K, you can and should pass some +EV spots, but if his stack is 800, you can and should take some -EV spots.
This is probably obvious to anyone who gets it, and anyone who doesn't will think it's totally wrong. But I think that, at least in games where players are reasonably unwilling to gamble it up, it's very true.