1
general::
Phrase(s): run-of-the-mill
common or average; typical. • The restaurant we went to was nothing special—just run-of-themill. • The service was good, but the food was run-of-themill or worse.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Ordinary, average, as in There's nothing special about these singers? they're just run of the mill. This expression alludes to fabrics coming directly from a mill without having been sorted or inspected for quality. It has survived such similar phrases as run of the mine and run of the kiln, for the products of mines and kilns. [Late 1800s]
American Heritage Idioms