Aaron Cook spent the final month of last season and part of this winter removing a pause from his delivery. It is a cruel irony that even with smoother mechanics, his spring was interrupted with a sore right shoulder.

Manager Jim Tracy said after Sunday's soggy workout at Salt River Fields that Cook skipped his scheduled side session.

"(Trainer Keith Dugger) said it would be best if we just back off for a few days. There was a little something there, so we don't want to push it," Tracy said.

The longest-tenured pitcher in Rockies history, Cook arrived here at a crossroads. He went 6-8 with a 5.08 ERA last season and is in the final guaranteed year of his contract.

His 2010 season ended prematurely when the Reds' Joey Votto broke the pitcher's right fibula with a one-hop shot off Cook's leg.

The Rockies adopted a "less is more" throwing philosophy for their pitchers this spring in hopes of avoiding the shoulder injuries that struck Huston Street and Rafael Betancourt a year ago. The pitchers were restricted to 30 pitches in their first side session. They also have been forbidden from throwing breaking balls until their third session.