Losses in 11 of 15 games will lead to changes somewhere.Arizona will try to avoid its second four-game skid of the season Monday night when it opens a three-game series against the visiting New York Mets.After consecutive 81-81 seasons, the Diamondbacks (4-11) hoped to take a step forward and at least compete for a playoff spot in 2014. While there's still plenty of time left for that to happen, the team will need to find some solutions for a struggling rotation that has posted a major league-worst 7.18 ERA thus far.Those problems continued Sunday, as Trevor Cahill allowed seven runs over four innings in an 8-6 loss to the Dodgers. It was the fifth time in six games and ninth this season that an Arizona starter failed to complete six innings."The pitching, the starting pitching. Is there a question about that?" manager Kirk Gibson said. "We got five innings out of the guy today, four, that's tough. The one thing you want to go well is you want to get innings out of your starting pitchers."The Diamondbacks allowed 22 runs and struck out 34 times during the weekend sweep by the Dodgers. They have dropped eight of nine at home, including a pair of season-opening losses in Australia.Cahill is just one of several struggling Diamondbacks starters, prompting Gibson to remove Randall Delgado from the rotation after two starts and replace him with reliever Josh Collmenter (0-0, 2.25 ERA), who will make his first start since 2012 Monday.Collmenter is 13-12 with a 4.03 ERA in 35 career starts. He prepared for this switch by throwing 55 pitches in four scoreless innings of relief Wednesday at San Francisco. The right-hander also had a six-inning stint out of the bullpen in June against Miami."I take it in stride and I'll do whatever I can with the team to help out," Collmenter told the team's official website. "It's obviously nice to come back to the rotation. It's something not a whole lot of guys get to do once they are sent to the bullpen. To be able to go back and forth really helps out."One of Collmenter's 11 starts in 2012 came against the Mets, an 11-5 victory July 27. He allowed five runs and seven hits over six innings in that contest.David Wright is 2 for 9 against Collmenter but both hits were homers.Wright and the Mets (5-7) continue their nine-game trip after splitting the first six games in Atlanta and Anaheim. Sunday was a day Wright's club would rather forget after Bartolo Colon gave up four home runs as part of the Angels' 17-hit attack in a 14-2 rout."We've bounced back a couple times," Wright told the Mets' official website. "We've kind of given away a couple games that we should be winning. It's tough to take positives out of that, but at the end of the day, we're putting ourselves in position to win some games, and we need to take advantage of that."Reliever John Lannan also served up a home run Sunday, raising the Mets' total to a major league-high 22. Arizona ranks second with 20.After a quality start in his season debut, Zach Wheeler (0-2, 5.73) wasn't nearly as sharp against the Braves on Wednesday. He gave up four runs on eight hits over five innings with six strikeouts in a 4-3 loss.The right-hander was outstanding in his only start against the Diamondbacks, yielding one run over 6 1/3 innings in a 4-1 victory at Chase Field on Aug. 10. His only mistake in that outing was a home run to Aaron Hill.The Mets won four of seven against the Diamondbacks last season, taking the final two of a three-game set in Arizona in August.