SAN FRANCISCO -- The Giants began the unofficial second half of the season with as close to a sure thing as possible -- Madison Bumgarner starting at AT&T Park. His seven-inning gem against the Houston Astros, coupled with Buster Posey's Barry Bonds-like blast in the first inning showed the Giants needed no luck to earn a 5-1 win on Orange Friday the 13th.Starting pitching report:Madison Bumgarner is plain hard to hit at AT&T Park.The game started the way you want it to. One pitch, one All-Star retired as Jose Altuve flew out to fellow N.L. All-Star Melky Cabrera to start the game. Altuve, who was 5-for-11 with a home run against Bumgarner coming in, went 0-for-3 against the Giants' starter.Bumgarner allowed baserunners in each of the first three innings, but stranded them all. Then he settled into his steely groove, tossing three-up, three-down fourth, fifth and sixth innings. Bumgarner left plenty of Houston thumbs in the batters box, inducing multiple broken-bat ground balls.It looked to be more of the same in the seventh until, with two outs, Bumgarner elevated a 91-mph two-seam fastball to Chris Snyder, and Snyder got all of it, sending it deep into the AT&T alleyway down the left-field line to break up the shutout. It was the second and final hit Bumgarner allowed. Bumgarner got former Giant Matt Downs to fly out to right field to end the top of the inning and left the field for last time Friday to a standing ovation.Bumgarner's final line: Seven innings pitched, two hits, one earned run, two walks, five strikeouts, 105 pitches, 64 strikes and another dominant home win. He earned his 11th win on the season, matching Lance Lynn for second in the N.L.The 22-year-old southpaw is now to 15-2 in his last 18 home starts. He entered the game fourth in the National League with a home ERA of 1.88 (Ryan Vogelsong is first at 1.43).Bullpen report:Javier Lopez entered for Bumgarner in the eighth inning and struck out the only batter he faced, Brian Bogusevic. Lopez gave way to Sergio Romo, who retired Altuve on the first pitch and got Brian Bixler to strike out swinging. The best right- and left-handed specialist pairing in the majors showed why.The Giants scored a run in the ninth to eliminate the save situation, and it was Romo who trotted out for the final three outs. But after a single and a walk, Bochy elected to bring in his closer -- Santiago Casilla. Bochy said before the game that Casilla's blister is fully healed, and Casilla backed his manager's words by striking out Chris Johnson and Chris Snyder to end the game.With the bats:The Giants picked up where they left off in the All-Star game, scoring four times in the first two frames. It was more than the staff needed.After a first-inning walk to Ryan Theriot, Buster Posey faced Wandy Rodriguez with two outs and no respect. He clubbed an 89-mph two-seam fastball an estimated 448 feet to dead center field, sending the crowd into a nostalgic frenzy as the words "Barry Bonds" passed in whispers around the stadium like the forbidden wave. The crack of Posey's contact was Bonds-like, too.The blast was just the Giants' 15th at AT&T Park this season, and their ninth in the last 22 games. They entered Friday's game tied with the Dodgers for the least home runs in the majors (51).The second inning was just as productive as the first. Angel Pagan and Brandon Belt each slipped singles into left field and with Joaquin Arias in the box, Bruce Bochy called for the double steal. Without Pagan and Belt in motion, Arias' ground ball to third base is a 5-4-3 double play. Instead, Astros third baseman Chris Johnson broke for the bag and Arias' ground ball barely evaded the Pagan's head-long dive en route to the safety of the left-field grass. Pagan scored, Belt moved to third and the Giants were poised for a big inning with runners at the corners and Madison Bumgarner up with no outs. They only managed to make it 4-0, scoring Belt on Justin Christian's ground out.The Giants wasted three singles and two stolen bases in the middle innings before Nate Schierholtz -- who was hammering the ball in multiple batting practice sessions before the game -- led off the seventh with a triple. The Giants committed the Cardinal Offensive Sin and failed to score him.Pablo Sandoval gave them a chance for atonement when his drive down the right field line ended in a belly-slide into third base, his first non-All-Star Game triple of the season. Pagan sent a shallow fly to left field and Sandoval made the unwise decision to tag up. The ball beat him to home easily, but Sandoval went Jack Parkman in Major League and told Chris Snyder not to stand on the tracks while the train's coming through. The collision between 240-pounders resulted in a dislodged ball and Sandoval re-tagged home plate for the Giants' fifth and final run.With the gloves:Madison Bumgarner set the defensive tone in the first inning when J.D. Martinez lined a ball right back up the box. Bumgarner snared it with his glove, but with too much heat to be contained, it rattled out toward the first-base line. Bumgarner took a second to identify what happened before launching into action. He channeled Tim Lincecum, dropped into a double-knee slide around the ball, scooped it up barehanded and threw on to Brandon Belt to end the inning. Just like you draw it up.The Giants, who led the N.L. at the break with 69 errors, played clean defense behind Bumgarner.On the bases:After a two-out single in the fifth, Ryan Theriot stole his ninth base of the season. Melky Cabrera faked a bunt, and Theriot, who broke on Rodriguez's first move, slid in feet first. The extra 90 feet didn't matter, as Cabrera fanned on a low, sharp curveball.Angel Pagan was next to attempt after his two-out infield single in the sixth inning. Pagan, too, went on first move and his head-first dive barely beat Chris Snyder's throw for his 16th swiped bag this year.Theriot wasn't all impressive on the bases, though. Standing on first base in the seventh inning with Schierholtz on third, Theriot ran into a double play. He tried to put on the brakes and backtrack on a slow ground ball to second, but had gone too far to prevent Altuve from tagging him and retiring Melky Cabrera to end the inning with a 4-3 double play.Attendance:The announced attendance of 42,116 resembled a tiered pumpkin patch thanks to the orange fur headdress giveaways from Hanwha Solar on Fireworks Night.Up next:Saturday marks a big start for Tim Lincecum (3-10, 6.42), as GM Brian Sabean and manager Bruce Bochy acknowledged that if he cannot progress, his spot in the rotation could be in jeopardy. He'll face Lucas Harrell (7-6, 4.56) when the Astros visit the Giants in Game 2 of the three-game series Saturday at 6:05 p.m. Get it hot with Giants Pregame Live at 5:30 p.m. on Comcast SportsNet Bay Area.