Matt LeBlanc's character, Joey Tribbiani, underwent a crucial change in the early seasons of Friends that saved the sitcom in the long run. Initially introduced as a suave ladies' man and aspiring actor from a large Italian-American family, Joey's character was not as dumb as he later became known for. However, after a few episodes, Joey's intelligence was deliberately toned down to differentiate him from his best friend and roommate, Chandler. This change allowed the show's comedic dynamics to work, as it highlighted Joey's obliviousness and lack of common knowledge.
If Joey had remained too similar to Chandler, the chemistry between the six main characters would have suffered, and the show's success may have been at risk. Thankfully, the alteration to Joey's character helped to balance out the group dynamic and contributed to Friends' longevity and massive success, as the show ran for ten seasons.