Troy Tulowitzki and Carlos Gonzalez are also vital to the team's prospects.The Rockies could use another strong effort from the trio of sluggers Saturday night as they try to win back-to-back games against the visiting Arizona Diamondbacks for the first time in almost two years.Helton is 7 for 15 with three doubles and five RBIs in three victories for Colorado (3-4) in 2012, while he's gone 0 for 9 in defeats. The first baseman, whose 347 homers and 1,311 RBIs are the most in franchise history, had three hits and three RBIs on Friday as the Rockies rallied for a 7-6 win over Arizona (5-2).Helton, though, deflected praise to the bullpen, which yielded four hits in 6 1/3 scoreless innings while the Rockies erased an early four-run deficit."The bullpen was unbelievable. The bullpen won us the game," Helton said. "They were fabulous, especially when they had runners at second and third with nobody out. To get out of that, that's what won us the game."The entire Rockies lineup is proving a feast-or-famine proposition, batting .373 with 29 runs scored in the three wins compared to .177 with seven runs in the four losses.Tulowitzki, who went 3 for 4 on Friday to raise his season average to .333, has seen four of his nine hits go for extra bases. The All-Star shortstop is 8 for 16 with two homers and six RBIs in his last four games against the Diamondbacks.Gonzalez had two hits in the series opener, and is 6 for 14 with two triples and four RBIs in his last three games. He is batting .360 in 46 career games versus Arizona, going 11 for 25 over his last six.Gonzalez is 4 for 8 with two doubles and a homer off Josh Collmenter, Saturday's scheduled starter for Arizona.The Rockies will turn to Jhoulys Chacin in an effort to win consecutive games against Arizona for the first time since a four-game winning streak Aug. 21-Sept. 12, 2010.Chacin, though, has not won a single game since Aug. 28. The right-hander has posted a 4.50 ERA while losing all five of his starts since then, including Monday's 7-0 defeat to San Francisco. He lasted just four innings in his season debut, giving up four runs and five walks.Chacin is 3-2 with a 2.89 ERA in six career starts against Arizona, which is now trying to avoid its first back-to-back defeats of the season.Diamondbacks center fielder Chris Young will try to rebound from his first hitless effort after opening the season with a six-game hitting streak. He is batting .320 with three homers and seven RBIs.Collmenter was tagged for six runs in three innings against San Francisco on Sunday, a game Arizona won 7-6. Those struggles followed a poor spring training, during which the second-year right-hander went 0-4 with a 9.95 ERA in six starts.A start on the road doesn't seem ideal for Collmenter, who went 1-6 with a 3.46 ERA in 15 games away from home in 2011. He was 2-1 with a 3.04 ERA in four starts against Colorado, but both victories came in Arizona.