darrenbear,
For example when a new type is introduced its logical that there will be an intake of direct entry Captains and FO's but a good employer will also ringfence a given number or positions for internal candidates.
That sir, putting it nicely is simply not true. There is nothing logical about your statement and in any established airline it is simply not necessary nor is it standard practice.
Olbie is of course is quite correct with:
How is that logical? Where did SQ, EK or QF find experienced 380 drivers?
Without giving my game away, I have worked for one of those carriers and I can assure you that what you are talking about never happened there nor will it.