Simplify the following text for a Grade 8 native English-speaking person.
Original: Thompson appeared in only five games for the Bruins in the 1938 â `` 39 season , as Boston decided to replace the aging goaltender with the substantially younger Frank Brimsek .
Simplified: Thompson played only five games in the 1938 â `` 39 season , because the Bruins decided to replace him with Frank Brimsek .