The Chicago Cubs haven’t finalized their opening-day roster, but Monday’s trade of infielder Zach McKinstry to the Detroit Tigers opened up a spot for infielder Miles Mastrobuoni. McKinstry was sent to the Tigers for Carlos Guzman, a 24-year-old minor-league pitching prospect who posted a 4.11 ERA in 27 games last year with Class-A West Michigan and Double-A Erie. Mastrobuoni, a second baseman and right fielder, hit .333 with 2 RBIs in 18 games this spring.