Allietta was the starting catcher that night against the Oakland Athletics, and went 0-for-2 against Ken Holtzman. In the top of the 7th, Rollie Fingers was called in to face Allietta, and Bill Sudakis pinch hit for him.
The passage describes a baseball game where Allietta, the catcher, was facing Ken Holtzman in the top of the 7th inning.  Rollie Fingers came in to replace her, and Bill Sudakis pinch hit for him.