Posing and composing
Once you've got everything set up and the team assembled, it's time to actually arrange the athletes and pose them. Depending on how many people you're photographing there are several things you need to consider such as how to fill the image frame and how to make sure you can see everyone's faces.
Posing benches can make your life easier if you have them. If you don't, you still have options. One approach is to have the first row of athletes sit on the ground with their legs crossed. Have the second row kneel right behind them and the third row stand behind the second row. This, by the way, is where your arranging people by size helps out. You can take advantage of size differences to try and make the difference in heights between seated, kneeling and standing rows work in your favor. Often this means saving the shortest people for the standing row and using the tallest for the kneeling row, but this depends on the size differences of your athletes.
Next make sure each row is offset from the one in front of it so heads aren't blocked by the people in front. Making sure you can see everyone's faces is one of the most important parts of getting the team photo. While you're at it, either make sure the team isn't wearing its ball caps, or, if they insist on wearing them, make sure the hats don't obscure faces. You should be planning on using fill flash no matter what, but be sure to aim the flash so it cleans up any shadows from the bills of the ball caps.
Take a careful look at the background too. While it's nice if you can use something sport related as a background, that isn't always an option. If you have to work with what mother nature gives you, make sure it's as clean as possible (no branches or parking lots).
Photographing sports teams doesn't need to be difficult, just follow these tips and you'll be happy with the results!