SAN FRANCISCO -- Perhaps Oliver Perez isn't such an inconsistent pitcher after all. Perhaps the contrived term "pendulum-ic" doesn't apply to the Mets starter because, for three starts now, he hasn't performed so erratically. His performances haven't run from good to bad and back or even from bad to good and back. Instead, the progression has been this: unacceptable to poor to wholly inadequate.

Perez reached what the Mets only can hope is the nadir of his uneven season Monday night when he initiated the team's second West Coast excursion with a next-to-nothing start. With the have-not Giants in the other dugout and a left-handed pitcher on the mound, the Mets had reason to be encouraged, no matter the site and their understandable fatigue. But any semblance of positive was dispelled in the bottom of the first inning when Perez allowed six runs and retired one batter.

Repeat: six runs in one-third of an inning, which loosely translated into the language of Willie Randolph was: "A horrible night, a terrible, terrible outing."

Perez's cameo appearance was almost exclusively responsible for the 10-2 defeat that ensued. The Mets had come West with insufficient rest, except for Perez who had flown ahead by himself. They were leaning on their starting pitcher, asking for more than a starter is normally asked to provide -- set a tone, reduce some of the onus on the offense, make the job easier for the defense.

And Perez provided far less, sabotaging his colleagues.

The Mets played competitively despite the deficit Perez had created. But he had pushed them into a deep pit. Escape was impossible despite their conspicuous scrambling. Any notion they had of salvaging this game ended in the sixth and seventh innings when the Giants scored four times against Carlos Muniz. The fault hardly was his, though.

The responsibility began and ended with Perez, now a .500 pitcher -- his record is 4-4 -- on a once-again .500 team. With four losses in their 10 most recent games, the Mets have a 28-28 record. They didn't expect to stub their toe so badly, here by the Bay.

Perez identified it as "the worst start of my career," and no one took issue with the evaluation. His teammates couldn't know for sure. But how much worse could a start be? They took it on faith that six runs, five hits -- two of them home runs -- and three walks in an eight-batter sequence was a bottom-out performance.

The one-third inning was the shortest start of Perez's oft-blemished career, the shortest by a Mets pitcher since Tom Glavine's tortured start on the season's final game last year. Before Randolph performed euthanasia, Perez had surrendered a leadoff home run by Randy Winn, a two-run double by Ray Durham and a two-run home run by No. 7 hitter Brian Horwitz, a rookie. After Perez walked the No. 8 hitter, Randolph purposefully walked to mound, extended his hand toward his battered pitcher, wordlessly asking for the ball before any additional damage might occur. The manager acknowledged his displeasure.

"He wasn't competing, he was flailing away on the mound," Randolph said. "You can't just start heaving the ball. You have to make adjustments. That's what pitchers do."

Instead, Perez made it a short night, with an assist from his unsympathetic manager. He threw 36 pitches, so he is really rested now.

The poor first inning -- though this one was off the Ollie Charts -- was not an unfamiliar development. Perez's ERA for the season is hardly handsome, 5.70. But in the first inning, it is 9.53. The home runs were the 10th and 11th against him in what now is 60 innings this year. They also were the 14th and 15th he has allowed in the first inning since the beginning of last season, the most in the big leagues.

Perez was replaced by Claudio Vargas, who as a member of Brewers was the opposing starter the last time the Giants scored six runs in the first inning, Aug. 24 last year. But Vargas wasn't the losing pitcher in that game.

"You can overcome a bad start when you've got eight more innings," Randolph said. He thought his team had comeback in its blood.

The Mets played with vigor, which was quite gratifying for the manager who sometimes had seen less from his team in less trying circumstances. They made plays -- Ryan Church threw out two runners at second base -- and they challenged winning pitcher Jonathan Sanchez (4-3), the Giants' equivalent of Perez, scoring in the second and fourth innings.

"I was proud of that," Randolph said. "We did play them hard. It was a good sign."

The loss stung, nonetheless. Randolph suspects his team, even with its recent reversal, will need to squeeze every possible victory out of its remaining schedule.

The Mets have yet to demonstrate -- or even hint -- they are one of the league's upper echelon teams. Perez has had a hand in that, too.