Chacín, 34, had struggled to a 7.61 ERA in 47 1/3 innings of relief this season with Colorado. He began his pro career with the Rockies back in 2006 and returned this spring on a one-year, $1.25 million contract.

He'll take the spot of the injured Antonio Senzatela (knee) on the club's active roster. Chacín has posted a disappointing 7.36 ERA, 1.50 WHIP and 34/18 K/BB ratio over 44 innings with the big league club this season. He'll continue to function in a middle relief role.

The internet says that is "inflammation of the sesamoid bones in the ball of the foot" and surrounding tendons. It's unclear how long Chacín might be out. With ugly numbers in Colorado this year, he's probably not a trade candidate.

Chacín was forced into action early on Wednesday after Germán Márquez left with an injury concern -- possibly a blister -- with one out in the fourth inning. Both runs on his line scored on a two-run homer by Will Smith in the fifth. Across 26 appearances (36 innings) this season, Chacín has posted an uncomfortable 6.50 ERA and 1.33 WHIP. There is no fantasy upside, here.