Simplify the following text for a Grade 12 native English-speaking person.
Original: Following his breakthrough performance in Rocky , critic Roger Ebert had once said Stallone could become the next Marlon Brando , though he never quite recaptured the critical acclaim achieved with Rocky .
Simplified: Following his amazing performance in Rocky , critic Roger Ebert had once said Stallone could become the next Marlon Brando , although he never received the same critical praise achieved with Rocky .