For seven of the sixteen SNY broadcasts of Mets games during spring training there will be a different voice calling the play-by-play than the usual one belonging to Gary Cohen: Current analyst Ron Darling is going to give it a shot.
Darling decided to ask SNY executives for the opportunity after Kevin Burkhardt's departure at the end of last season. Darling said he is looking to increase his versatility in doing his job, and spring training is the perfect time for him to get a taste of play-by-play because of the lower stakes—and audience size—of the exhibition games. He also expressed optimism regarding his ability to do the job since he would still be working with Keith Hernandez, saying he "wouldn't have even thought of doing it unless I knew I was going to be doing it with Keith."
As of now, there are no plans for Darling to continue doing play-by-play during the regular season, though with some practice this spring he'd be more prepared to fill in should Gary Cohen need to skip a game or two.