"He's continuing to do some throwing, it's just a matter of his shoulder and the weakness," Rockies manager Jim Tracy said. "It has more to do with him building up strength and continuing to do that than anything else.
"He'll have days where he feels really good, and then he'll have other days when he feels somewhat of a weakness in his shoulder. So we're mindful of that."
Smith was sent to the Minors at the end of March but hasn't pitched in a game since May 25 at Triple-A Colorado Springs. With the Sky Sox on an 11-game road trip, the left-hander made the trek up Interstate 25 for a 60-pitch session at Coors.
The simulated game could have gone smoother.
"I wouldn't say it's the best he has felt," head athletic Trainer Keith Dugger said. "He got fatigued a little bit."
The club will check with Smith on Wednesday to determine if he's ready to return to pitching in the Minor Leagues. If not, Smith will try another simulated game. There is no need to rush him given the recent success of fourth and fifth starters Jorge De La Rosa and Jason Hammel.
Nick Zaccardi is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.