Conversation so far:
When did Roger Clemens join the Red Sox?
1986.
How did he perform in his first season on the Red Sox?
The 1986 ALCS clincher was Clemens' first postseason career victory.
How much was he paid by the Red Sox?
CANNOTANSWER.
How long was Clemens on the Red Sox?
1995.
What team did he join after the Red Sox?
CANNOTANSWER.

Question: Why did he leave the Red Sox?
Self-contained rewrite: Why did Roger Clemens leave the Red Sox?