Ryan Zimmerman stood 30 feet away from Matt Eiden, the Washington Nationals’ assistant strength coach and, for the moment, his guinea pig of a throwing partner. It was mid-January and Zimmerman had not thrown a baseball for months, not since the shoulder surgery he underwent in November. He would find out now, in the batting cage at Nationals Park, the state of his rebuilt right arm. Zimmerman took a step. He cocked the ball behind his ear. He thought, “Please be okay, please be okay, please be okay.” He swung his arm forward . . . and spiked the ball into the ground. The ball barely rolled to Eiden. “It was really funny after the second one was okay,” Zimmerman said. “At first, we were just like, ‘Whoa.’ ” Zimmerman laughed about the story Friday afternoon as he fixed a tuna sandwich in the home clubhouse of Space Coast Stadium. He has not spiked another throw since in his recovery from the operation. His throwing arm now brings him optimism rather than frustration. In a Nationals camp defined by expectations cranked to nosebleed altitude, Zimmerman, 28, possesses a modest hope. He wants to feel normal again on a baseball diamond, the way he had always felt before last year. As he played last season through cortisone shots to numb the pain in his right shoulder, Zimmerman’s arm would not move in the way his brain told it to. His throwing motion turned into a Frankenstein monster, a series of movements patched together solely to keep him on the field. He made 12 throwing errors, reduced from a defensive whiz to a question mark.