"Not very good obviously. Any time you're giving up balls out of the park you're not doing a very good job," Collmenter said. "I haven't been doing a good job of controlling counts and getting ahead and making them hit my pitch."
Early on this season, Collmenter had no problem keeping hitters in the ballpark, allowing just one home run in his first five starts. Since then, the D-backs' Opening Day starter has allowed 12 over his last seven outings.
That stretch started when Collmenter allowed three homers in a win over the Rockies on May 6, which was his previous career high. That was also the last time the right-hander notched a win. In six starts since then, he is 0-3 with a 7.76 ERA.
"Ball's up and if he's up and out over the plate, they get him," D-backs manager Chip Hale said. "He's either got to get it up and in or up and cutting it off the plate where they swing and chase it. He just hasn't had good location and big league hitters, they'll hurt you."
Collmenter was just the second D-backs starter to complete six innings in the last eight games -- Jeremy Hellickson went six in Friday's win over the Mets. The last time a D-backs starter lasted longer than six frames was on May 24 when Hellickson pitched 6 2/3 innings against the Cubs.
On the fourth pitch of the game, Collmenter gave up the first of two home runs to Curtis Granderson. The D-backs scored two runs in the bottom of the first to take the lead, but Collmenter immediately gave it back when he allowed a two-run shot to Eric Campbell in the second.
"You never want to give up runs, especially early in the game," Collmenter said. "If you give up runs before these guys even have a chance to hit, it puts them behind the eight ball, so you want to try to go out there and put up zeroes early."
Collmenter said he feels he knows what he needs to do to get back on track.
"Just try to get a good feel for throwing the ball and throwing the ball down and away," Collmenter said. "If you can get strikes early, it's huge, so I need to be able to do that with my secondary stuff."