Germany and Spain have about 32% foreign players, England has at least 65% that in a nut shell is the problem.
Does this come down to poor youth development, and that we aren't developing good enough youth?
Take England Rugby - One of the top teams in the world, and rugby has a lot of academies for a less popular sport seems to outnumber the football academies.
Each area has a RFU development officer, who's job is to work on local talent even in areas where rugby is not popular.
In my area there is a number of top quality rugby academies with a number of players going on for Premiership rugby and England. Yet I am unaware of any such quality football academies.