Simplify the following text for a Grade 10 native English-speaking person.
Original: The defense , led by Jack Lambert , Mel Blount , Jack Ham and Mean Joe Greene , gave up fewer points than any other American Football Conference team in Pittsburgh 's Super Bowl seasons of 1974 and 1975 .
Simplified: The unit , led by Jack Lambert , Mel Blount , Jack Ham and Mean Joe Greene , gave up fewer points than any other American Football Conference team in Pittsburgh 's Super Bowl seasons of 1974 and 1975 .