Conversation so far:
How did Hoyt  Wilhelm get started in baseball?
Though Wilhelm was primarily a starting pitcher in the minor leagues.
What team did he first play for?
Wilhelm made his MLB debut with the Giants.
Did he have a  favorite pitch?
CANNOTANSWER.

Question: Who was he playing at his first at bat?
Self-contained rewrite: Who was Hoyt Wilhelm playing at his first at bat?