I want to know the answer to the following question:
What new rule was put into practice during the 2010-11 season?
All the background I'm provided with is that "As of the 2010–11 season, the Premier League introduced new rules mandating that each club must register a maximum 25-man squad of players aged over 21, with the squad list only allowed to be changed in transfer windows or in exceptional circumstances.". Is that enough to answer the question?
Answer: yes