Stadiums:

This appears to be a feature that either wasn't implemented very well or it is very difficult to obtain.  Several TCY players have had long careers where there stadium is sold out a good portion of the time and still have not received any stadium upgrades.

Other Users that hasve received stadium upgrades usually see this after a poor year (1-10) or (2-9) this is not highly recommended as you could lose your job but after a poor season you may get a bigger stadium.

The only good thing is that it seems like you can raise your ticket prices very high after your team is consistantly good and increase revenues a great deal.