After compiling a 14.14 ERA in his first three spring starts, the Arizona right-hander is working on improving command of his fastball.
The D-backs asked Collmenter to improve his curveball, so as to give him an added weapon to go with his fastball and changeup. Up until this point in the spring, he had focused on his offspeed stuff.
"I guess our concern has been that maybe he worked too much on that, and he's lost the feel for his fastball a little bit," Arizona manager Kirk Gibson said. "He's always been outstanding at location, you guys know that, and he hasn't had that yet."
Collmenter missed a start earlier this spring with tightness in his forearm, but he said that has not been a factor in his struggles.
"Everything keys off my fastball," he said. "If my fastball is down in the zone, my curveball and changeup look a lot better."
Gibson reiterated that Collmenter will be in the rotation to begin the season.
"He's our fifth starter," Gibson said. "If he's not healthy, then we'll have a change. He tells me he's healthy. We'll watch."
While Collmenter knows his spot in the rotation does not depend on his performance, he still would like to have better results.
"You just want to make better pitches," Collmenter said. "The big thing for me is just consistency. I'm not going to be a guy that throws pitches by guys and strikes a lot of guys out, so I just have to make better pitches. The ones I've made down in the zone, I've gotten good results. It's just a matter of consistently making those."