Villarreal got sent down to Triple-A Louisville despite posting a 2.25 ERA in eight spring training appearances.
Villarreal was stymied by not being on the Reds' 40-man roster. "That poses part of the challenge," Reds manager Bryan Price said. "A lot of factors went into the decision. That No. 1, was a consideration -- creating roster spots for guys and having some flexibility with the guys we have on the roster. The other part is as we shrink this down, there are guys we really wanted to see first."