CBC Radio 3 reveals the reason for the somewhat surreal job assignment. The Los Angeles Dodgers have another Andre Ethier in their employ, although he's more of a right fielder and less of a rock musician. When a member of the Dodgers organization discovered the Deadly Snakes singer via a web search the invitation was made to unite the Andre Ethiers of the world at the game. Naturally, the Dodgers will be playing the Toronto Blue Jays.
Lead Radio 3 personality Grant Lawrence (singer for the Smugglers) interviewed Andre about the request. You can check that out here. The Deadly Snakes released their swan song Porcella in 2005. Ethier's second solo album secondathallum hit last year.