(Mike Ehrmann/GETTY IMAGES)

Cameron would have provided the Nationals the right-handed half of a possible center field platoon. Without him, the Nationals will turn to other options and a different approach. Against left-handed starters, Rizzo said, the Nationals could shift Jayson Werth to center field and play veteran Mark DeRosa. (That, though, would inhibit Manager Davey Johnson’s plan to give Adam LaRoche ample rest by playing DeRosa at first against lefties.)

Other right-handed hitters could receive a better chance to make the Nationals’ roster. “There are some candidates that we’re interested to look at,” Rizzo said, identifying Jason Michaels and Brett Carroll by name. Andres Blanco, a candidate to become the Nationals’ utility infielder, has experience in the outfield, but Rizzo said the Nationals do not plan on playing him there.

The Nationals were not caught off guard by Cameron’s decision. Cameron, 39, called Rizzo on Wednesday and told him he had started leaning toward retirement after 17 seasons. He wanted to watch his son play high school baseball, and preparing for another marathon season was unpalatable.

“He just wasn’t physically or mentally motivated get prepared for the season,” Rizzo said. “I told him to sit on it for a day or two, see if you change your mind. He didn’t. I thanked him for being so professional. He just didn’t want to come in here and not give it 110 percent and embarrass himself. He’s to the end a true professional. I thought it was a classy move for him to not come in and not be Mike Cameron.”