ME: Does Jose Leclerc count? He had a breakout year last year, but this is his first full season as a closer. Repeat last year's performance and he will cement himself in the upper echelon of young closers. That would be huge.
After that, it's slim pickings, mostly because the bullpen has a bunch of veterans. The couple of young guys -- Kyle Bird and Kyle Dowdy -- are kind of at the back end of the pecking order. Bird will be shuttled back and forth to Triple-A as need be. Brett Martin might also get some looks this season in the bullpen as part of the shuttle to reinforce the staff.