A new feature in iOS 10.3 allows apps to request permission to change their icons after they’ve been installed, and the latest version of MLB.com At Bat and the NHL app are taking full advantage of it, according to 9to5Mac. Both apps will allow you to choose your favorite team and change the home screen icon to the logo of the corresponding team with a few clicks.
Once you open either app (and have downloaded iOS 10.3) click on More > Settings > Home Screen Icon, and select your preferred team. Once you head back to your home screen, the icon will be refreshed. It’s a neat trick in iOS 10.3, but sadly it won’t work with your favorite third-party calendar or weather apps, as those types of active icon changes aren’t allowed just yet.