MLB Rookie Profile: Dayan Diaz, RHP, Houston Astros

On Sunday the Houston Astros promoted relief pitcher Dayan Diaz to the major league roster. He came out of the bullpen to pitch two-thirds of an inning against the New York Yankees, fanning two but giving up three hits and three runs, one unearned. he was then sent back to Triple-A after the game. Can we expect better? Let’s take a look.

Dayan Diaz was originally signed by the Astros as a free agent from Colombia in 2005. He spent three years in the Venezuelan Summer League, fought injuries, and didn’t really emerge as a prospect until 2012 when he posted a 1.85 ERA and 19 saves in the South Atlantic League. He then drifted as a minor league free agent, spending time in the Chicago Cubs, Boston Red Sox, and Cincinnati Reds organizations.

He performed decently in 2016, posting a 3.05 ERA with a 46/16 K/BB in 56 innings for Triple-A Louisville in the Reds system. He received a brief MLB trial last year, giving up nine runs in 6.2 innings with a 3/7 K/BB, then returned to the Astros system for 2017 as a free agent. After pitching for Colombia in the World Baseball Classic this spring, he had a 1.98 ERA in 13.2 innings in Triple-A this season, 15/5 K/BB, before his latest promotion.

Listed at 5-10, 195, Diaz possesses a four-seam fastball between 90 and 96 MPH, averaging 94. He has two secondary pitches, a slider and a change-up, both working in the mid-to-upper-80s. In the minors he’s done a good job throwing strikes and has been successful, but has been more tentative in the major leagues.

In general Diaz has a classic middle relief/mop-up profile, projecting as an 11th or 12th man in a modern bullpen.

A brief clip from his MLB debut with the Reds last year: