What happened: Jerry Koosman, a cornerstone left-handed pitcher for the 1969 World Series championship team, has died. The two-time All-Star spent the first 12 seasons of his career with the New York Mets and earned induction into the team's Hall of Fame.

Why it matters: Koosman anchored the New York rotation during the franchise's first championship era and remains one of the defining pitchers in club history. His decade-plus run in Queens established enduring benchmarks for franchise starters following the 1969 title.

What to watch: The Mets and Major League Baseball are expected to announce memorial plans and franchise tributes.