2) Padres pitcher Drew Carlton won't be on the roster by June 1st
Optional relievers are treated extremely unfairly. They bounce back and forth from Triple-A to the majors more than anybody, and are often overworked. Drew Carlton fits into this category. Eventually, a Padres starter won't give much length, the team will be behind by a lot, and they'll need someone to eat the innings. That will be Carlton's job.
The right-hander provided length when the Padres really needed it in a game earlier this month against the Royals. Seth Lugo got roughed up, allowing five runs in just two innings of work. The Padres called on Carlton to try and give them the length Lugo failed to give, and he came through.
In his three innings of work, he gave up two hits and struck out three without walking a batter. He kept the Padres in it, and San Diego nearly mounted a comeback. His reward for that outing has been sitting in the bullpen to wait for his next appearance.
Carlton has just that one appearance, and will eventually get sent down for a fresh arm. He won't necessarily deserve it, but that's how this game works.
The good news for him is he'll likely be back. Carlton will go up and down until the Padres can't manipulate that anymore. Hopefully he'll pitch well in his limited chances.