I've just tested the plugin and I should say it's a great one!
But I have a problem. I wanted to test if the point system works properly and that's why I created a game trying to predict it. I entered some random score and the message "Changes saved." appears but it's like it doesn't really saved my prediction...
Then I've tried to set the date of the game somewhere in the next 2-3 days and it worked fine - I could predict the games. After few more tests, I found out the problem. I am using UTC+3 in my General WP settings and that's why all the games has to be predicted at least 3 hours before the game.
Sorry for my English, I am applying three screens so you could understand what I mean in an easier way:
Before I made my predictions: http://store.picbg.net/pubpic/F5/78/fe144c29eaeff578.jpg
During the action:
And after clicking the "Save" button:
This was made at 1:15 the same day. The game that is going to be played after ~9hours is saved but the one that will be played after ~1h is not... And my tests say that this is because it's in the 3h timezone difference.
Hope to hear from you and sorry for being that detailed