I am probably over simplifying things here, but could the answer be money?

Imagine a Premier team need a new striker or whatever

Is it possible that the transfer fee for a player from a foreign team would be a lot less than for a player of equal talent and ability from another Premier team or even from a lower division.

I may have got it wrong, but just a thought.

And quite a few of our home grown players are now playing overseas.

There could be a similar thread running on a forum in another country, regarding the number of English names on jerseys..