Keller pitched at three levels in 2018, finishing last year in Triple-A before heading to Fall League. The Marlins added him to their 40-Man Roster after the season to protect him from the Rule 5 Draft. He’s a power-armed reliever with a two-pitch mix, equipped with a 93-to-97 mph fastball and hard slider. Keller’s raw stuff is enough for a leverage ‘pen role, but continued control issues likely limit the degree he can be trusted with runners on late in games. If he can throw enough strikes, Keller has the tools to factor in to Miami’s bullpen mix in the near future as a middle reliever.