PITTSBURGH (AP) -- Dan Straily knew before he went to work on Tuesday night his next start wouldn't be in the majors. The All-Star break and a quirk in the Oakland Athletics' schedule means the AL West leaders won't need a fifth starter for a couple of weeks.
Before hopping a plane for Triple-A Sacramento, the rookie right-hander left a little something to remember him by. Straily (6-2) allowed two hits over 6 1-3 innings, striking out seven and walking three to win his fifth straight decision.
''I could have thrown a perfect game and I was going to get optioned out,'' Straily said. ''It's nothing personal. It's the situation we're in. It is what it is.''
The A's called up right-hander Sonny Gray to take Straily's spot, hoping the 2011 first-round draft pick can get some work out of the bullpen over the next couple of weeks. That apparently wasn't an option for Straily.
Oakland manager Bob Melvin called having someone at the back end of the rotation with Straily's talent a ''luxury,'' one the team can apparently live without until later in the month.
''That's the life of a fifth starter,'' Melvin said.
Even if Straily isn't exactly pitching like one at the moment for the A's, who have won 10 of 13. He tossed seven shutout innings in a victory over the Chicago Cubs in his previous start, then backed it up by silencing the quickly cooling Pirates. Straily credited a much-improved curveball for keeping the Pirates off balance.
''(Pitching coach) Curt (Young) said in passing in my last bullpen that he thought my curve was good and that I should use it more in games,'' Straily said. ''It's something I've worked on a lot and you're always trying to get better, but last year I put the curve on the shelf because I was working on the changeup so much.''
Straily threw just one changeup against the Pirates, and Pedro Alvarez sent it 448 feet to center in the second for Pittsburgh's lone run.
''I didn't throw another one after that, so the curveball gave me a third option,'' Straily said.
Grant Balfour worked the ninth to remain perfect in 24 save chances this season. Brandon Moss slammed a two-run homer in the fourth off Gerrit Cole (4-2) to supply all the offense Oakland required.
Moss spent parts of three seasons with the Pirates between 2008-10, with Pittsburgh hoping his raw left-handed power would help him pound balls off - or over - the Clemente Wall in right field.
It never really happened. Moss hit all of 13 homers in 195 games for the Pirates before eventually making his way to Oakland, where he's become a key cog in one of baseball's biggest surprises.
Moss provided a glimpse of what could have been in Pittsburgh in the fourth when Cole wobbled for the briefest of moments. The right-hander had retired nine straight when John Jaso doubled with two outs. Moss followed with his 16th home run of the season, though he hardly viewed it as some sort of revenge.
''I had a lot of opportunities here and I didn't do anything with them,'' Moss said. ''It's my fault that I'm not here anymore.''
Pittsburgh had hoped to break loose against Straily, who has struggled starting on four days' rest during his brief major league career. Straily came in 0-3 with a 7.16 ERA when not given at least five days between starts.
Yet he had no issues dealing with Pittsburgh's suddenly punchless offense. The Pirates have scored just six runs during a 2-6 slump that has dropped them behind first-place St. Louis in the heated NL Central race.
Alvarez provided Pittsburgh's lone run with his drive to the bushes in center leading off the second. The home run made him the third player in team history to reach 23 homers before the All-Star break, joining Ralph Kiner and Willie Stargell.
The Pirates didn't get a runner to third base over the final six innings. Their best chance to tie the game came in the seventh when Alvarez led off with a walk and moved to second on Russell Martin's sacrifice bunt. Oakland reliever Sean Doolittle replaced Straily and struck out pinch-hitter Gaby Sanchez before getting Jordy Mercer to pop up to first.
Jose Tabata led off the ninth with a single off Balfour, but Andrew McCutchen and Alvarez struck out before Martin grounded out meekly to first as Balfour extended his club record for consecutive save chances converted to 42, dating to last season.
NOTES: The start of the game was pushed back due to the potential of inclement weather. While lightning flashed several times during the 1:42 delay, it never actually rained. ... Oakland LF Yoenis Cespedes was selected to the American League team for the Home Run Derby next Monday night in New York. Cespedes, who has 15 home runs this season, is the first A's player to be chosen for the Home Run Derby since Jason Giambi in 2001. ... McCutchen went 0 for 3, ending his 10-game hitting streak. ... The series wraps up Wednesday when Pittsburgh LHP Francisco Liriano (8-3, 2.20 ERA) faces Oakland LHP Tommy Milone (8-7, 4.11). ... Hall of Fame golfer Arnold Palmer, who grew up in Latrobe, about 45 minutes east of Pittsburgh, was in attendance.