As for Yoenis Cespedes, Alderson added: "Right now I'm not counting on him playing any right field."
Conforto has played left field exclusively during his professional career. At Oregon State, he played right field seven times as a freshman in 2012. He also appeared once at third base, during his junior year in 2014. De Aza has appeared in 74 games (52 starts) in right field during his eight-year major league career.
"It's possible you'll see Conforto over there in spring training a couple of times," Alderson said. "We'll just have to see how it shakes out. De Aza could be over there."
Alderson said Cespedes may end up following the same playing pattern he did last year after joining the Mets -- starting in center field against right-handed pitching, and starting in left field against left-handed pitching (with Juan Lagares in center field).
"We had a conversation prior to reaching agreement to confirm that he was willing to play center field again," Alderson said. "We were able to confirm that."
Cespedes played center field in Cuba, so he is familiar with that position. Alderson figures Cespedes' fielding in center will be improved compared with the final two months of 2015 because Cespedes will now have a full spring training to get further reacquainted.
"He came in cold during the season last year and played center field," Alderson said. "He's going to have a whole spring training. He's played out there before but hadn't recently when we acquired him. So I think there's every chance he'll be somewhat better defensively this year than he was last year."
On Conforto playing against at least some left-handed pitching, Alderson added: "I would foresee that. I think it's a little premature to say, 'Well, Conforto is going to play every day.' He's going to have to earn that right."