Sweeney urges discipline for card-happy England

• England ranks second-best in the world when maintaining 15 players on the pitch.
• Rugby Football Union chief executive Bill Sweeney highlights the importance of discipline.
• Sweeney's comments come in response to England's tendency to receive cards.
• The focus is on improving performance by keeping all players on the field.
• Sweeney's statement aims to address and rectify the issue of card incidents.