At some point, coaches dream it. What if … the unexpected happens, and out of the blue a great athlete walks into the program? No fanfare or competition for his services, just somebody no one knew about who can really play. But it was no dream for Kingsley Claudy, boys volleyball coach at Monterey Trail High School. Last fall, one of the school's top players, Johnathan Nguyen, sprinted up to the coach and said in so many words a volleyball star had arrived, special delivery from the Czech Republic. Name of Marek Slavik. Mad skills.

Claudy asked Slavik, a 6-foot-4 exchange student from the village of Rosovice, to hit a few volleyballs. The 18-year-old obliterated them as onlookers ducked for cover. "Right away...