Bang the Drum Slowly (1973)

When hotshot pitcher Henry Wiggen (Michael Moriarty) is signed to the New York Mammoths, his confident ways quickly win over his teammates. He's quite the opposite of Bruce Pearson (Robert De Niro), the team's simpleminded catcher, who has difficulty connecting with others. But when Henry discovers that Bruce has been hiding that he was recently diagnosed with a fatal form of cancer, the unlikely pair become close. Despite Henry's efforts to look out for Bruce, however, team tensions rise.