Either the album rating is the mean of the track ratings or the track ratings are randomly generated with the album rating as the mean. I'm not sure which.

the pettiest penalties known to man:
Too many count offs → lose ½ a star from each re-offender
... → song loses 1 star
Sudden deafening noise lawnmowers etc. → song loses 1 star
... → song loses 2½ stars
... → album loses 1 star