Otherwise, the Mets must pay them $100,000 to go to the minor leagues, or release them.
Scott Atchison was signed to a minor league deal this winter, but since he was non-tendered by the Red Sox in December, he will not have to be informed until camp breaks (like most other non-roster invitees).
I expect Byrdak will take his $100,000 and remain with the Mets so he can continue his rehab from shoulder surgery. He has said he is ahead of schedule in his rehab, and could be pitching by June or July. Whether that's the case and what he will be when he returns is a mystery, but there's no harm in keeping him and seeing what happens.
As for the others, Terry Collins has said all spring he and the staff are more comfortable going with veterans with track records in the bullpen, and Feliciano, Hawkins and Atchison fit that criteria. If the Mets are comfortable with Feliciano’s reduced velocity, he will probably make the team — he has the most experience of any of the other candidates. If he does go north with the club, the Mets need to be careful how Feliciano is used going forward – he should only be used against left-handed hitters, and certainly not at the rate he was used in his first go-around with the Mets. They can easily send Robert Carson to the minor leagues, get him some more work, and call him up later — if or when — a need arises.