I would say that in the tens of thousands of minutes I have played basketball, that being clutch comes from having experience and not that being experienced comes from being clutch. So I totally disagree with you.
Your argument is a ridiculous one. You become experienced by having all sorts of experiences: lop-sided blowouts, nailbiters, watching form the bench, playing horse, etc. It all gives you experience. You don't just get experience by playing in a tight game.
Once I scored a basket that still makes me laugh.