Collmenter followed up a rough spring with a pair of sub-par starts, the most recent being Saturday night when he allowed five runs and five hits over four innings.
"He's going to start Thursday," D-backs manager Kirk Gibson said. "He's done it in the past, we have confidence in him. He's had two starts and he didn't have a good spring, but we believe he can do it. He knows how to get guys out."
The struggles have begun to take their toll on Collmenter mentally. Rather than just let his muscle memory take over and relax, he's been too conscious about his mechanics.
"I'm just trying to think of too many things rather than just throwing the ball," Collmenter said. "Just from pitch to pitch, how I need to stay back or make this pitch here instead of just letting your body just do what it does naturally. It becomes clogged up with thoughts."
The bottom line for Collmenter is that he has to put his pitches where he wants to, because he does not have the overpowering, pure stuff that could make up for poor location.
"The biggest thing for me, and it's been the same theme all the way through Spring Training, is just lack of location," he said. "I rely on feel a lot as a pitcher, and guiding the ball where I want, and putting it where I want. My feel and rhythm and tempo from outing to outing and sometimes even inning to inning feels different or off."
Collmenter said that physically he feels fine, and it appears that he is better pitching out of the windup than out of the stretch when he feels like his body is going in different directions.