Complex sentence: Unlike his long-time contemporary, Chick Hearn, who criticized his Los Angeles Lakers when he felt warranted, Most rarely criticized the Celtics during game play but wasn't shy about criticizing other teams' players.
Split into simpler sentences: Unlike his long-time contemporary, Chick Hearn, who criticized his Los Angeles Lakers when he felt warranted, Most rarely criticized the Celtics during gameplay. But he wasn't shy about criticizing other teams' players.