The Dead Sea Effect
The Dead Sea Effect on Bruce F. Webster
"... [T]he more talented and effective IT engineers are the ones most likely to leave - to evaporate ... [those who tend to] remain behind [are] the 'residue' — the least talented and effective IT engineers."
Bruce F. Webster
The "Dead Sea Effect" suggests that in any organisation, the skills/talent/efficacy of engineers is often inversely proportional to their time in the company.
Typically, highly skilled engineers find it easy to gain employment elsewhere and are the first to do so. Engineers who have obsolete or weak skills will tend to remain with the company, as finding employment elsewhere is difficult. This is particularly pronounced if they have gained incremental pay rises over their time in the company, as it can be challenging to get equivalent remuneration elsewhere.