Having started things off right with their first-half ace last night, the Yankees give the ball to the man they hope will be their second-half ace this afternoon, Joba Chamberlain. As a full-fledgedstarter, Joba has a 2.57 ERA in 35 innings with 38 strikeouts and just 32 hits (only five of which have gone for extra bases as opponents are slugging .302 against him). His 4.11 BB/9 remains a small concern, but he didn’t walk anyone in his last start, which saw him strike out nine in 6 2/3 innings (108 pitches). The Yankees are 4-2 in Joba’s six full-length starts, but Joba is only 1-1, both the result of the fact that Chamberlain has received more than two runs of support just twice in those six outings.

Perhaps concerned about wasting a Justin Duchscherer start by pitching him against Chamberlain, the A’s have moved their remaining ace to tomorrow’s game and will instead start Sean Gallagher, the pitcher obtained from the Cubs in the Rich Harden deal. Like Joba, Gallagher is a 22-year-old righty who’s built like a brick shithouse (both are 6’2″ and roughly 230 pounds). Unlike Joba, Gallagher doesn’t have overwhelming stuff. Still, there are a lot of things to like about Gallagher. He dominated the Angels in his first AL start (7 IP, 2 H, 2 R, 3 BB, 7 K). In 11 major league starts dating back to May 11 of this year, he has a 4.23 ERA and a 1.28 WHIP, solid numbers for a 22-year-old rookie starter. Even more impressive, he has allowed just five home runs in those 11 starts and none in his four starts at Wrigley Field. Opponents are hitting just .235/.314/.385 against him and he doesn’t show much in the way of a platoon split. Perhaps most importantly, Gallagher hasn’t had any real disaster starts. His shortest outing after his first start has been 4 2/3 innings, and he’s never allowed more than five runs in a game.

Jorge Posada is back behind the plate, clearing room for Jason Giambi at DH and Wilson Betemit, who appears to be Richie Sexson’s platoon parter, at first base. The A’s, meanwhile, have made a few roster moves that have made my series preview out of date. Bobby Crosby was activated before yesterday’s game. He returns to shortstop with Donnie Murphy riding pine and Gregorio Petit getting optioned to Sacramento. Today, first baseman Daric Barton was place on the DL with a strained neck and Wes Bankston was recalled to play first. Finally, it is lefty Lenny DiNardo who will wind up taking Joe Blanton’s spot in the rotation, making fellow southpaw Dallas Braden, who gave up Alex Rodriguez’s home run yesterday, the replacement for Chad Gaudin in the bullpen.