I love the idea of Rob Valetini going 'jeez, JOC (James O'Connor) has missed a penalty from 40 out on the angle in the 15th minute. I don't know if I've got it in me now. What's the point? This game is done.'
I would expect you to be right. A professional rugby player should just have a "Oh shit" moment and then get on with 100% focus.
On the other hand, confidence can be an illusory thing. Perhaps a missed goal, which was easy by Test standards, was just enough to prick the confidence bubble.
All the subsequent handling errors, stupid niggle, and wrong decision making had to be caused by something, and a lack of training isn't it. Mental approach may have played its part.
A sports psychologist I aint, just a rugby theorist.