2.
bat a thousand: a reference to a continuing series of successes, alluding to a baseball player who gets on base every time at bat
3.
box score: a count or summary (from the chart on
which a games statistical details are recorded; applicable to various
sports but originating in reference to baseball)
4.
bush league: (not of the highest quality or sophistication) - a sports organization subordinate to
the major leagues (referring to the usually rural locations of such
teams; can apply to any sport but originated in reference to baseball)
5.
curve ball: something unexpected (from the unpredictable trajectory of that type of baseball pitch)
6.
go to bat for: support (from the notion of a batter contributing to his team)
9.
in the ballpark: close; said of an estimate (compared to being within the confines of a stadium)