mine-run

[Kathleen E. Miller]

Last Week - Justice R.B. Ginsburg , "so long as the rule, like the mine run
of procedural rules, generally serves the state interest."

4/19/01 Newsday, "Brian Daubach strokes a three-run homer during Boston's
mine-run eighth inning."

3/11/01 News & Record, "They do tend to make ordinary, mine-run politicians
look a little dingy by comparison."

07/18/94 American Lawyer Newspapers Group, "In the 'mine run' of cases it
may not be so very difficult because more or less similar cases have blazed
trails."

Sometimes this seems to mean vast majority - others just run-of-the-mill
ordinary - and the baseball one is, well - what exactly does this phrase
mean, and where did it come from?