Tanaka's presence represented one of the few energizing forces for the club in the loss. Although his appearance in left field was just his 10th since 2006 -- manager Bruce Bochy said he will strictly roam left field for the Giants -- he made a dazzling catch against the wall to rob Andrew Brown of an extra-base hit in the second inning.
"It's exciting to see someone make a strong debut, especially someone as established as him," Barry Zito said. "He's been around, and he just has that excitement when he plays and that's what we need."
Tanaka recorded his first Major League hit in the fifth inning with a bloop single to center field. Two innings later, he led off with a walk and scored to tie the game on a Pablo Sandoval sacrifice fly.
"I came here to bring something new to the team," said Tanaka, with the lineup card and baseball from his first hit lying on the chair beside him.
Even his smile was infectious, and that can't be a bad thing for a team that's dropped 18 of its last 23. When he came down with the ball in his glove after the second-inning catch, he pumped his fist and let out an I-can't-believe-I-just-caught-that grin.
"I was just glad to catch the ball," Tanaka said through an interpreter.
But in the end the Giants' smiles subsided and the stark reality of a team desperate for answers sunk in. Zito could not continue his success at AT&T Park -- he allowed five runs at home for the first time in 17 regular-season outings -- and a fatigued bullpen allowed the go-ahead run in the eighth inning.
Daniel Murphy lifted a fly ball just deep enough to left-center to allow Omar Quintanilla to score from third. After walking David Wright, Marlon Byrd gave the Mets bullpen four more insurance runs on a grand slam on the first offering from Jake Dunning.
"[The pitch] just didn't break," Bochy said. "He didn't get it where he wanted it. Jake's done such a nice job for us. He made a mistake and he hasn't thrown many."
It was another puzzling outing for left-handed reliever Jeremy Affeldt, who is typically a key cog in the bullpen but has struggled in recent weeks. After inheriting Jose Mijares' runner, Affeldt yielded a single to Juan Lagares, a walk to Eric Young Jr. and the go-ahead run on Murphy's sacrifice fly before walking Wright to load the bases and hand the ball to Dunning.
"It seems like everything we try to do ends up not being a positive outcome for us," Affeldt said. "Right now, I might be the biggest issue in that.
"We're giving up more runs than we're scoring and I'm a big part of that. It stinks, to be honest. I really stink."
For the second straight night, the Giants grabbed an early 2-0 lead and squandered it. Zito's errant command in the fourth inning ignited the Mets' offense for three runs, highlighted by Brown's two-run single. Twice the Giants fought their way back to tie the game, but twice the Mets had an answer.
"It was my job to hold them down and I wasn't able to do that," said Zito, who added that walks were his biggest issue Tuesday.
With the game tied at 3 and Zito's pitch count nearing 100 in the sixth, he walked Mets first baseman Josh Satin and surrendered a home run to catcher Anthony Recker, an earlier strikeout victim.
"Recker got me on the same pitch I got him on earlier," Zito said. "Sometimes that stuff happens."
With former Giants first-round Draft pick Zack Wheeler on the mound for the Mets on Wednesday as New York attempts to sweep in San Francisco for the first time since 1994, Bochy dismissed the idea that his club feels overly discouraged.
"No, I'll never feel like that," Bochy said. "We're being tested like we've never been tested before."