First, the new names. The Rockies have called up Jairo Diaz, who the Rockies received from the Angels in return for Josh Rutledge this past offseason. Diaz is a fireballer who can dial it up to 99 mph, but that doesn't mean he hasn't been hittable, and it also doesn't mean he has command. He has a 4.58 ERA this season for Triple-A Albuquerque. He's struck out about eight batters per nine innings, but he's also walked six per nine. Also, Diaz has received "experience" as a suffix, so this should be interesting, if nothing else.
Oh, @Rockies fans, now you get to witness the Jairo Diaz Experience up close.— Chris Jackson (@TopesWriter) August 23, 2015
The Rockies have also purchased the contract of Simon Castro. Castro was signed in April to a minor league contract. The big righty has posted a 3.79 ERA in 57 Triple-A innings this season.
To make room for Diaz, the Rockies optioned reliever Justin Miller. Castro, however, needed a spot on the 40 man roster. To make room, the Rockies designated Rafael Betancourt for assignment, according to Dargan Southard.
Against a whole bunch of odds, Betancourt returned from Tommy John surgery after missing all of 2014 to make the Opening Day roster. He was effective at times. Like he's done for his entire career, Betancourt saw success with pinpoint control, which led to a lot of whiffs and weak contact.
Overall, however, Betancourt far more hittable this season than in the past. In 39 1/3 innings this season, Betancourt posted a 6.18 ERA, which was partly the product of the opponent slugging .455 against his fastball with an isolated power against of .190. Still, Betancourt was probably the victim of some poor luck, as his strand rate was only 52.8 percent. But what can be cast as poor luck for some players might mean a decline in ability for others.
We'll have more about Betancourt soon. Despite this season and the unceremonious end, Betancourt is one of the best relievers in Rockies history.