SAN FRANCISCO -- Michael Wacha missed on a pitch to Marlon Byrd -- hanging a curveball that cost him four unearned runs -- and was unable to ring up his 16th win of the season on Friday night to match Madison Bumgarner and Jake Arrieta for the National League lead.
But what Wacha did before the Giants prevailed, 5-4, on Kelby Tomlinson's walk-off single in the ninth outweighed what he did not do. The Cardinals' 24-year-old right-hander from Texarkana, Texas, showed why he's a legitimate No. 1 on the best pitching staff in the game.
Wacha returned to AT&T Park, the scene of his NL Championship Series accident last October, and kept his team in an important game against the defending World Series champions. He did it with his competitive will as much as with his skill, which is of the highest order.
"I was excited about coming back here," Wacha said, "trying to get a win for the club this time."
Wacha's work was done when the Giants prevailed against a Cards bullpen that has stood its ground with the Royals as the game's best.
While the Giants remained 2 1/2 games behind the Dodgers in the NL West and moved to within 4 1/2 games of the Cubs for the second NL Wild Card spot, the Cardinals watched their NL Central lead dip to 3 1/2 games over the Pirates.
"It's not the usual for us," Cards manager Mike Matheny said, referring to errors by third baseman Matt Carpenter and shortstop Jhonny Peralta that set up Byrd's eighth career grand slam in the third inning. "Michael did a great job of keeping his composure and picking up the defense. It's just one we couldn't steal."
This happened while the local telecast was airing the classic walk-off home run by Travis Ishikawa in Game 5 of the 2014 NLCS, sending the Giants on to a World Series triumph against the Royals. Wacha, victimized on that memorable blast, was shown walking slowly toward the dugout as the ballpark erupted.
Ten months later, Wacha walked tall off the mound, having done a highly professional job of controlling damage.
"I felt really good out there," Wacha said. "Errors happen in games. I try to take it on myself to get out of those innings and pick up my team. I wasn't able to do that tonight."
Wacha's 15-4 record and 2.69 ERA in 25 starts are evidence that he has let go of October and has rebounded nicely, in every way, from that season-ending jolt by Ishikawa.
There was, naturally, disappointment in the events of Friday night. Wacha wishes he could have put more bite on that first-pitch hanging hook to Byrd.
"I left that one up in the zone," Wacha said, "and Byrd made me pay for it."
With help from his normally steady, cooperative teammates, Wacha would not have been engaging Byrd in the third inning. It would have been a 1-2-3 inning rather than a mess.
Wacha didn't help matters by drilling Posey with a first-pitch fastball to load the bases. Byrd unloaded to center for his second home run in two days. He had been hitless in 17 at-bats against Wacha, who surrendered his first career grand slam.
Byrd is the latest example of the Giants' remarkable fortune with in-season acquisitions: Cody Ross in 2010, Marco Scutaro in '12, Jake Peavy in '14. All three played a major role in a run to the World Series championship.
Mike Leake, another newcomer moving comfortably into the Giants' rotation behind Bumgarner and Peavy, was in fine form in his confrontation with the Cardinals' young stalwart.
Leake, like Wacha, was harmed by a double play that wasn't turned in a three-run fourth punctuated by rookie Stephen Piscotty's first-pitch, two-out, two-run double. Tommy Pham manufactured a run in the sixth with aggressive baserunning after a leadoff single.
"There's never a doubt in our dugout," Wacha said. "After the four-spot went up, the energy was as high as it always is. That's awesome for a pitcher. I gave up those runs, and the team comes back and fights for you."
Wacha is on a roll when it counts. Over his past six starts, covering 39 innings, he has yielded just four earned runs for a 0.92 ERA.
The long-term forecast in St. Louis with Wacha atop the rotation is for clear skies and good times -- just as it is in The City by the Bay, home of the champs. These are model organizations, the best the sport has to offer.
Lyle Spencer is a national reporter and columnist for MLB.com. Follow him on Twitter @LyleMSpencer. This story was not subject to the approval of Major League Baseball or its clubs.