The Red Sox signed infielder Justin Turner to a one-year contract on Friday, adding a player they hope can help make up for the loss of All-Star infielder Xander Bogaerts in free agency. Left-hander Darwinzon Hernandez was designated for assignment to make room on the 40-man roster. The addition of the 38-year-old Turner comes on the heels of Boston agreeing to an 11-year contract worth $331 million with Rafael Devers to stay with the Red Sox, a person with knowledge of the agreement told The Associated Press on Wednesday.