Simplify the following text for a Grade 9 native English-speaking person.
Original: Unfortunately the Austrian 's serious accident in 1994 seemed to have taken a lot out of his driving potential and he was replaced after two races by rookie Jean-Christophe Boullion .
Simplified: Wendlinger 's accident in 1994 seemed to have reduced his driving potential and he was replaced rookie Jean-Christophe Boullion .