Some things to watch out for:
-If you already have a report in the news/html/leagues (?) folder, then in pre-season we won't generate a new one. I don't remember when this folder gets cleared.
-If you go to the page in spring training and it doesn't generate a new report, go to that folder above, delete the old file, and go back to the prediction page in-game. It should regenerate it.
-The game will force generation on opening day if you have the option set, even if there was a file there, I think, so if you manually generate a prediction in spring, and then go back after opening day, it may be different.
-Prediction report will be done based on how the rosters are currently set. So if your top RF is hurt and on the DL, he won't play in the prediction report. So don't trust it too much