The right-hander looks for his first win with Oakland on Friday night in the opener of a three-game series with the free-falling Texas Rangers.The major league-leading Athletics (63-38) acquired Hammel and fellow starting pitcher Jeff Samardzija from Chicago on July 4, hours after Hammel pitched the Cubs to a 7-2 win in Washington.That victory moved him to 8-5 with a 2.98 ERA, but he's dropped his first two starts with Oakland behind a 9.00 ERA. He made his team debut July 9 at San Francisco, and while Hammel allowed two earned runs over five innings of a 5-2 defeat, he was bothered by a cramp in the thumb on his glove hand.His next start came 10 days later due to the All-Star break, and it was a short one. Hammel lasted a season-low two innings, allowing five runs and six hits -- two homers -- in an 8-4 home loss to Baltimore on Saturday.He's walked five in seven innings with Oakland after averaging 1.9 walks per nine innings in 17 starts with the Cubs."I'm just not pitching like myself right now, which is fastball command," Hammel said. "This is one I have to go home and forget. I'll come back ... and go back to work."Hammel gets back to work against Texas, which has dropped 27 of 32 and is 22 games under .500 (40-62) for the first time since the final week of the 1988 season. He's 0-1 with a 9.82 ERA in one start and one relief appearance versus the Rangers, last facing them in 2008.Oakland enters this series after Samardzija went eight innings and Brandon Moss hit his third grand slam of the season in a 13-1 win over visiting Houston on Thursday. The Athletics have won four of six since the break and are a season-best 25 games over .500.Texas returns home after losing the last three of a four-game set at Yankee Stadium. The Rangers have dropped eight in a row in Arlington for the first time since a nine-game slide in 1990.Jerome Williams will try to pitch them to a rare win in his team debut. The veteran right-hander was released by the Astros earlier this month after going 1-4 with a 6.04 ERA in 26 relief appearances."We signed him, he's ready to go. We'll take a look at him tomorrow and see if he can help us," manager Ron Washington said after Thursday's 4-2 loss."I know Jerome Williams, faced him enough times to know what he's capable of. We'll see what he has to offer."Williams is 4-5 with a 4.19 ERA in 16 games against Oakland, starting nine times. He allowed five runs and 10 hits over seven innings in three matchups in April.Catcher Derek Norris is 11 for 23 with a homer, five doubles and nine RBIs in seven games against Texas this season. Center fielder Coco Crisp is 13 for 30 with a home run, four doubles and six RBIs while also playing in seven of the nine meetings with the Rangers.The Athletics have won five of the last six matchups after the Rangers swept a three-game series in Oakland from April 21-23.