Mariners 21-year-old rookie superstar Julio Rodríguez left tonight’s game with lower back tightness, furthering the saga that began earlier this week. As reported by Daniel Kramer of MLB.com, Rodríguez did not undergo an MRI when he first experienced the lower back tightness over the weekend in Anaheim, but is now scheduled to receive imaging tomorrow in Kansas City. When asked about Rodríguez after the game, Mariners manager Scott Servais labeled the young star’s back troubles as “concerning.” Rodríguez is having a fantastic start to his career, slashing .279/.341/.499 for an OPS of .840 and a WRC+ of 143, the second…