Simplify the following text for a Grade 8 native English-speaking person.
Original: After three subpar games in Weeks 2 -- 4 , Warner was replaced at quarterback by rookie Matt Leinart in the fourth quarter of Week 4 .
Simplified: After Matt Leinart played poorly in the three games of Weeks 2-4 , Warner replaced the rookie Leinart in the fourth quarter of Week 4 .