Hello Mick,
Thanks for contacting us!
You can’t exactly have 10 different calendars on one site, as there is one central calendar at http://yoursite.com/calendar for example. However, two solutions come immediately to mind.
If you use the Filter Bar plugin you can assign two categories to each game event, one for each team. Then users could filter the calendar for the team they want to see (you can also link them to filtered calendars).
The other solution, depending on the size and scope of you league, would be to use WordPress Multisite to create a site for each team. Then you can have a dedicated calendar for each team
Does this make sense? Let me know if I can explain anything else!
Cheers!
– Casey Driscoll