The Boston Red Sox demoted Japanese right-hander Naoyuki Uwasawa back to Triple-A Worcester on Wednesday. Boston removed the 30-year-old from its 26-man Major League Baseball roster to free up a spot for starting pitcher Nick Pivetta’s return from the injured list. Uwasawa made his MLB debut for the Red Sox on May 2 and pitched four innings of relief over two games, striking out three while allowing one run on two hits for a 2.25 ERA. He was traded to Boston on March 27 by the Tampa Bay Rays, who initially signed him following his posting to the U.S. majors by the Pacific League’s Nippon Ham F…