Rockies reliever Jairo Diaz will undergo Tommy John surgery

For the second consecutive year, the Colorado Rockies will lose a hard-throwing reliever to an early season elbow injury and subsequent Tommy John surgery.

Right-handed reliever Jairo Diaz, who was expected to contend for a key spot in the Rockies' bullpen in 2016, will instead sit out the year -- and likely part of next season -- as a result of an ulnar collateral ligament injury that will result in the dreaded procedure, per MLB.com's Thomas Harding. Diaz lasted just two-thirds of an inning in his appearance on Saturday against the San Diego Padres, who scored three runs on three hits and three walks during that time.

Diaz threw a higher percentage of sliders than usual, perhaps in response to instructions from the coaching staff. That's nothing new for spring training, and certainly the coaches aren't to blame; the situation is just yet another example of the poor injury luck that has plagued the Rockies in recent years.

Adam Ottavino is still recovering from his April 2015 operation, and Tyler Chatwood is finally getting back into game action after undergoing the surgery in 2014.

With Diaz out, the already-strong chances of guys like Scott Oberg and Justin Miller making the team out of spring training go up exponentially. It could also open the door for a prospect such as Carlos Estevez or Nelson Gonzalez to contribute at the major league level earlier than initially planned.

Diaz, 24, owns a 2.55 ERA with 26 strikeouts and nine walks in 24⅔ big league innings. In parts of six minor league seasons, the Venezuela native has posted a 5.26 ERA with 7.9 K/9 and 3.7 BB/9.