We’ve seen hockey played outside in stadium. And there’s been some basketball outside too. While tennis is generally outside, it doesn’t often take place in MLB stadiums. The USTA is changing that this weekend by building a red clay court in the outfield of San Diego’s Petco Park for a Davis Cup tie. This is a trend we’ll see continue. Read more about the clay-court build and the future of tennis in stadiums in my Sports Illustrated article.