Instead, Ishikawa -- who broke from third on a grounder to Mets third baseman David Wright and appeared to slide under Blanco's tag after the catcher had to jump to get Wright's high throw -- was called out by home-plate umpire Phil Cuzzi in the bottom of the ninth inning with the score tied at 3.
Cuzzi gave Ishikawa no further explanation. "He just said 'out,'" Ishikawa said.
The same went for Giants manager Bruce Bochy, who argued the call.
"He missed it. He said he was safe. Not much you can do," Bochy said. "He thought [Wright] got him."
Even Blanco was shocked.
"I was surprised when he called him out," Blanco said. "He was safe all the way."
Television replays -- and from a different angle, so, too, did the naked eye -- showed afterward that Ishikawa slid under the tag, but instead of picking up a season-high sixth straight win and sweeping the Mets, the Giants went to extra innings.
It was there, with two outs in the top of the 10th, that New York's Ike Davis hit Brian Wilson's 3-2 slider off the right-center-field wall to score Jason Bay and give the Mets a 4-3, extra-inning win Sunday afternoon at AT&T Park.
Ishikawa said he saw the replay, and while it was closer than he initially thought, he still was disappointed in not earning the win.
"To feel like I was so sure the game was over was just a satisfying feeling, and then I started celebrating early because I thought I beat it, but when he raised his hand for the out, my emotions got the best of me and I started arguing with him a little bit," Ishikawa said. "But I calmed down a little bit. ... These guys, they have a tough job to do. ... Today it just feels like we were on the short end of the stick."
Cuzzi said afterward that he thought Ishikawa's leg never touched the plate.
"He made a decent attempt to put the tag on him," Cuzzi said of Blanco. "That's what it looked to me, and that's why I called him out."
Down 3-1 in the bottom of the ninth, the Giants already had let other scoring opportunities go to waste, finishing the day hitting 1-for-15 with runners in scoring position.
After scoring in the first inning on a sacrifice fly by Buster Posey, the Giants failed numerous times to get the job done. Pablo Sandoval led off the second inning with a double, but three consecutive Giants followed with strikeouts. In the third, the Giants put runners on first and second with one out but failed to score and also led off the sixth with back-to-back singles without scoring a run.
They finally got the big hit they had been waiting for in the ninth.
Sandoval drew a leadoff walk to begin the ninth-inning rally, but left after Juan Uribe's single with a tight right hip. Sandoval said afterward he'd be able to play Monday.
Eli Whiteside followed Uribe's single with a well-executed bunt, and Ishikawa drilled a two-run single to center to tie the game.
Andres Torres also doubled, moving Ishikawa to third, before Ishikawa was called out.
"We had some opportunities and we kept missing the big hit and we finally got it in the ninth," Bochy said. "That's one that hurts because we thought the game was over."
Wilson came on in the 10th but after getting two quick outs gave up a single to Bay and then the game-winning hit to Davis.
"Whatever the umpire calls I feel is the right call; I don't really second guess that," Wilson said. "But ultimately I take full responsibility for that loss. I still could have made a good 3-2 pitch."
Despite Cuzzi's blown call and Wilson's second loss of the season, Sunday's loss was just the club's second in its past 11 games. That stretch began after another tough game, San Francisco's grinding 15-inning loss against Colorado on July 4.
"This club's been resilient. We showed it last road trip and now we have to bounce back from this one," said Bochy, whose club now goes on the road for three games with the Dodgers and four with the D-backs. "This was a tough one. This is one we had and I feel for those guys because they battled hard. But we've got to be ready to go [Monday] and we know we have to play better in our division and put this behind us."