From the Economist:
The [English] Premier League's main source of strength is its financial clout. Since the early 1990s, when stadiums were upgraded and lucrative broadcasting deals agreed upon, the league has become a money-spinner. Foreign investors have poured in (Liverpool and Manchester United are owned by Americans, Chelsea by a Russian). England's big four clubs are among the world's ten richest, according to Deloitte, an accounting firm. This allows the clubs to hire the best players, which in turn draws crowds and increases revenues.
In most industries such a virtuous circle would be a cause for celebration. But Sepp Blatter, the president of FIFA, football's governing body, cites English dominance of the Champions League as proof of the need to restrict how many foreigners a team may field. Michel Platini, the head of UEFA, the European wing of FIFA, concurs. Some old-style hoof-it English managers claim that import restrictions would somehow help the coaching of young British talent.
This is the sort of protectionist tosh that most industries have not dared utter in public since the 1970s. How could a sport get better by limiting competition or lowering standards? English children are bad at football mainly because their training is bad (something other places have fixed). The league football in Britain is unimaginably better than it was. With luck EU labour law will stop Mr Blatter and keep it that way.
I think there are two points here. First, there is the notion that "import restrictions would somehow help the coaching of young British talent." This seems like the classic "infant industry" argument for import protection for goods, but applied to athletes: we need to keep out foreign athletes, so as to nurture domestic athletes and allow them to catch up to the level of foreign competition. I don't follow European sports leagues that closely (most of the articles I read on the subject are in the Economist!), but I've seen stories like this before. What I always wonder is, why I have never heard these issues come up in relation to American sports leagues? Maybe it's because the level of foreign participation is still fairly low, especially in sports like basketball and football (it is rising in basketball, though). In baseball, however, my sense is that foreign participation is significant, and I've never heard concerns expressed.
Hockey is a particularly interesting example in this context. NHL hockey teams, including the many American-based ones, used to be dominated by Canadians. Now, by contrast, there is a significant American (and also European) presence, probably in part because Americans were exposed to high quality hockey over the years (probably also in part due to improved hockey facilities in the somewhat warmer U.S. over the years). Maybe there's a good lesson for the English leagues there.
The second point is a bit different: "English dominance of the Champions League as proof of the need to restrict how many foreigners a team may field." The argument here appears to be that, in the absence of restrictions on labor mobility, rich leagues can buy up all the good players. In my view, this is a very different issue. Fundamentally, the issue is competition between teams with vastly different levels of financial resources. However, I'm not sure that restrictions on signing foreigners is the best way to deal with problem.