I've blogged on a couple of occasions about the issue of in-match data in soccer that is collected by sports data companies and considered proprietary information. It presents a complication in soccer analytics because of the traditional lack of statistics surrounding the game.
American sports have more historical team and player data of individual matches than other sports, but even so they provide an incomplete picture of what happened. This is especially true in complex invasion sports like American football or basketball. In today's Wall Street Journal there is an article on a specific camera feed in the NFL -- the "All 22" feed, a camera view of the entire field that shows all 22 players -- whose access is restricted to NFL teams and select partners (like, say, analysts on NFL Network). As the game has transitioned from a running game to a passing one, the All 22 feed has become more valuable in assessing team and individual play. The NFL has made strong statements that access to the All 22 will never be made public, even after commissioning surveys to gauge fan interest in paid access to selected (and selectively blurred) clips.
The article goes on to explain the NFL's stance, which is essentially that they want to protect coaches and players from further scrutiny -- not just scrutiny from the hardcore fans, but also from former players. Another possible explanation is that if the NFL controls the data, they can also control who has access to it, and those who have access will do their best not to lose it by doing something to antagonize the league. So in a stats-hungry sporting culture like the USA, the NFL have the killer negotiating chip.
Just a reminder that soccer teams and data companies are not alone in restricting access to sports data, and they may not be all that restrictive compared to monopolies like the NFL.