[lucozade]

Not the parent nor a professional coach but you wrote: "my daughter came to me in tears and complained coach is yelling at her".

That doesn't sound like being selected for stress tolerance. That sounds a lot more like stress tolerance is being mentally beaten into them.

[helge9210]

Selection is for physical capabilities (experienced coaches are actually looking at both parents in addition to child assessment). Stress tolerance is built up gradually as a side effect.