I am a die hard baseball fan (Cards), and I don't mind the exposition one bit. The more the show can draw in non-baseball-fan viewers, the better. And, they are at least striving for authenticity (admittedly with some sacrifices for TV and some errors, such as not getting "beanball" right) -- as others have said, the same can't be said for most shows. They often tip their hat to people who do know baseball.
Case in point: I was giddy, GIDDY that this episode featured the Cardinals... this was not an accident. Part of the legacy, for better or for worse. (Bob Gibson, the legendary Cards pitcher, described his pitching repertoire (nay, 'arsenal') as containing the brushback, hit-batter, and knockdown pitches, but emphatically NOT the beanball -- "Nobody in his right mind throws a rock 90-plus miles an hour at a guy's head.")