Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1957 , the BBWAA first defined the term as someone with fewer than 75 at bats or 45 innings pitched in any Major League season before the current season .
Simplified: In 1957 , the term was first defined as someone with fewer than 75 at bats or 45 innings pitched in any previous Major League season .