Diaz was designated for assignment by the Rockies on Thursday, Patrick Saunders of The Denver Post reports.
The Rockies officially signed right-hander Jhoulys Chacin to a major-league contract Thursday, and Diaz was removed from the 40-man roster in a corresponding move. Diaz posted a 10.24 ERA and 2.17 WHIP in 9.2 innings during nine relief appearances this spring and will likely report to the team's alternate training site if he goes unclaimed on waivers.