He is getting paid because of his 1999 (26 homers, .285) and 2000 (41 homers, .263) seasons.
Since then, Batista has hit .207, .266, .244, .235, .230.
Could you imagine being a pro athlete? You have 1-2 decent seasons (especially in a contract year), and you'll probably get at least $20-30 million, regardless of your future performance.