you can see a screenshot of the tournament selection here :
The up & down arrows let you select the displayed week. You can select any tournament at any time (once you finished your current one
Your stats go slightly down every week.
So if you don't play for a very long time, you'll finish with 0% everywhere.
But anyway, you have to not play tournament regularly, coz it gives you free days to do training, and raise your stats again.
You can also have a look at the full documentation (to read more details about the training, for example) :
http://managames.com/tennis/doc/Tennis_ ... .html#tour