It is a non-displaced fracture, and Tracy says that Cook is not necessarily done for the year.
Tracy says Jeff Francis will start Monday in place of Cook when the Rockies play the San Diego Padres. Francis has been out since Aug. 11 with soreness in his left biceps. He made one rehab start at Triple-A.
The Rockies went into Thursday trailing San Diego by 4½ games in the NL West and also 4½ games behind the Atlanta Braves for the wild card.