Arizona Diamondbacks manager Kirk Gibson simply wants some stability in his rotation.Locke takes the mound as Pittsburgh seeks a seventh straight home victory Saturday while facing Diamondbacks starter Trevor Cahill, who returns after a nearly seven-week stint on the disabled list.Pittsburgh (72-49) leads the competitive NL Central by three games largely because of a 3.12 ERA that is the best in baseball. It had lost five of its previous six but busted out of its slump after rookie Gerrit Cole pitched six solid innings in Friday's 6-2 win over Arizona.Pedro Alvarez drove in two runs and Jose Tabata hit a two-run homer after going 3 for 3 off the bench in Thursday's loss to St. Louis."I know people are saying the Pittsburgh Pirates need a right fielder," said Tabata, who was 2 for his last 14 prior to Thursday. "It makes me feel like I've got to do something. I just want to help my team win."The Pirates rank second in the majors with a 2.69 ERA at home, including a 2.29 mark during a six-game winning streak at PNC Park. Pittsburgh has won six of Locke's seven starts there, and he'll be on the hill again Saturday trying to give his team its first seven-game run at home since April 27-May 12, 2008.Locke (9-3, 2.43 ERA), though, had gone 0-1 with a 4.96 ERA over his previous three starts before giving up two runs -- one earned -- in 5 2/3 innings of Pittsburgh's 3-2 loss to Colorado on Sunday."(Sunday) was definitely a step back in the right direction mechanically, mentally," Locke said. "Everything felt back to normal."Despite Locke's four walks, manager Clint Hurdle focused more on the fact the left-hander allowed fewer than three earned runs for the 16th time."I'm real impressed with Locke's outing," Hurdle said. "Better tempo, better rhythm."Locke has yet to start against the Diamondbacks (62-58), though he pitched 2 1/3 scoreless innings of relief in the Pirates' 6-3 loss Aug. 9, 2012.Arizona's pitching staff, meanwhile, has dealt with injuries to Cahill (3-10, 4.66) and Brandon McCarthy while also shipping Ian Kennedy to San Diego at the trade deadline. The starters have a 4.68 ERA in August, and Gibson is hoping Cahill can help improve that number.Cahill hasn't pitched since giving up six runs in 4 1/3 innings of a 6-2 loss to Atlanta on June 30. He went on the disabled list the following day with a right hip contusion, which he reportedly suffered after getting hit with a line drive that forced him to leave his start June 19.Prior to going on the DL, Cahill went 0-6 with a 7.91 ERA over his last eight starts. Gibson, though, is confident the right-hander can bounce back."He's got good stuff," Gibson told the team's official website. "We need him to throw the ball good and be consistent and go deeper in games for us, and to have our rotation kind of solidified."Cahill wasn't at his best against the Pirates on April 8, giving up four runs in five innings of a 5-3 loss despite striking out seven.The Diamondbacks had won six of their previous eight but mustered only five hits in Friday's defeat. Cliff Pennington started for shortstop Didi Gregorius, who is 2 for 29 (.069) over his last eight.Pittsburgh has won three of the four meetings this season.
Jeff Locke (PIT): 2 2/3 IP, 8 ER; had not allowed more than 4 ER in any of his previous 23 starts this season. His 2nd half ERA is now 5.56 through 6 starts after posting a 2.15 ERA through his first 18.