There was a thrilling audacity about what Serena and Venus Williams attempted at Wimbledon this year. Sidelined by illness and injury for 11 and five months, respectively, the Williams sisters chose the sport’s grandest stage to return to competition with only minimal preparation. The decision was much like their shots: bold and full of risk, given their sterling resumes at the All England club, where they have combined to win nine of the last 11 Wimbledon titles.