A number of HR Directors have all asked me the same question; "How can we be so bad at predicting potential?"
The answer is simple; it's not possible to predict potential, any more than it is possible to predict the lottery numbers. No matter how well we think we know someone, we cann't guarantee what they will do in the next five minutes, never mind the next five years.
Psychometric tools and assessment centres do not enable you to 'know' someone; they enable you to categorise people.
I've been working on a research project, and also working with students at Aston University, to understand more about talent and leadership. This has revealed some fascinating insights into how we predict future potential, and what we can do differently to make better predictions and get some Return on Investment out of talent programs.