Your milk statements from the plant carry more meaning than how big the check will be at the end of the month. You already know that fat and protein test averages tell volumes about effective fiber, ration digestibility, protein, and carbohydrate balance, as well as many other factors, such as fat levels in the diet.
The variability of these component values can be as telling, if not more so, than the monthly or weekly averages. Variations in milk fat, protein percentage, and milk urea nitrogen can also point out effects of crowding, heat stress, large meal sizes and slug feeding, and inconsistencies in feeding times or accuracy of total mixed ration formulation.
In the December 2015 Wisconsin Agriculturist article Consistency matters as much as production, UW-Extension Wood County Agriculture Agent Matt Lippert discusses how to use your own herd as a benchmark and to account for sources of variability.