There is extensive research which shows that capability is the key driver of job performance.
Extensive research by the likes of Professors Daniel Goleman, John E Hunter and Frank L Schmidt conclusively show that psychometric assessments of cognitive and emotional capabilities vastly improve recruitment and selection decisions.
Past performance is a poor predictor of capability or potential for future roles.
Objectively understanding an individual's cognitive and emotional capability - they key drivers of job performance - are far better predictors of performance against future roles.
Understanding the capability that resides within various job levels, is key to understanding why organisations may be underperforming.