On the eve of Miro Rys’s second professional game in the North American Soccer League in May 1976, the veterans on his Chicago Sting team decided to play a prank, telling their 18-year-old teammate that it was customary for rookies to speak during dinner.

Perhaps missing the joke, the lanky left-footer from the Chicago suburbs improvised an earnest, unembarrassed speech, expressing gratitude at being picked to travel with the team that would face Pelé’s New York Cosmos in Yankee Stadium the next day. Instead of laughs, he...