Jarvis Martin, a Witness, started off wobbly, walking the Prophets’ lead-off man, Dustin Rigsby, then letting Rigsby take second on a wild pitch. A drizzle pattered on a few umbrellas as darkness began to creep over Lafreniere Park in Metairie, La., on a late July evening. Parents shouted encouragement to their 10- and 11-year-olds. So did the coaches, each wearing…