> ...catcher's balk...
There's no such thing as a catcher's balk; you made it up. A balk is when
the pitcher deceives the base runners by interrupting
his pitching motion so that he can throw to one of the
bases instead. The penalty is that the base runners are
each awarded an extra base. But the batter never advances to
first on a balk.
The seven you listed is the same as what I came up with.
a referred me to a web page that purported to list ten,
but I decided that three of them were no good.
(The best of the lot was that the batted ball might hit a runner,
but I believe that's scored as a hit regardless.)
I guess this has nothing to do with Perl. Maybe I'll get
on the worst nodes list!