Rafael Martin

Martin finally got his first crack at the majors in 2015, and while his 18.2 K/9 rate in 12.1 innings is certainly eye-opening, don't pencil him as the Nationals' next closer just yet. The 31-year-old, who joined the Nationals organization in 2010 after three years in the Mexican League, no longer has the 96 mph fastball that initially got him attention from major league clubs; instead, he gets by on a cutter and outstanding slider that helped him to rack up a 47-inning scoreless streak in 2014. He also gave up four home runs in those 12.3 innings, so the jury is still out on whether his arsenal is strong enough to allow success in the big leagues. The Nats bullpen will likely be overhauled after its collapse last year, so Martin will head into spring training with a good shot at winning a middle relief job, but he still has some things to prove in order to break camp on the staff.

Martin's story is pure Hollywood: he played just one year of high school baseball and then worked in the construction industry for four years, pitching on weekends in a men's league, before winding up as a pro in the Mexican League after attending a tryout on a whim. Three years later, he's hitting 96 mph on a radar gun and getting attention from MLB clubs, eventually signing with the Nationals. If the fairy tale doesn't come crashing back down to reality in Triple-A, don't be surprised if Martin makes his highly improbable major league debut in 2010.