Boggs, taking the injured Adam Wainwright's place in the rotation, had won three starts on the road, including the last two in succession in Boston and in Kansas City. But he is winless in two starts at home, and Thursday's defeat was his first as a major-leaguer.
Pitching too defensively, Boggs threw 50 balls out of 108 pitches.
"He had several things go wrong," said manager Tony La Russa. "The encouraging thing is that they're all fixable."
Boggs, 24, said, "You walk guys anywhere, they're going to score. You walk guys in Little League, they're going to score.
"You can't do that here. You can't do that anywhere.
"I got behind and tried to be too perfect. Especially these guys, if you get behind and have to throw pitches they're sitting there waiting for, you're going to get beat."
Ordinarily, Boggs would have come out of the game in the third inning when it already was 9-0, but La Russa made him stay out there.
"I would rather save him the beating when it's not his night," said La Russa, "but I was much more concerned about the effect on the rest of our pitching staff trying to finish that game."
The Cardinals' bullpen has had plenty of work lately, with three of the previous four starters failing to last past the fifth inning. And the Chicago Cubs are coming to town Friday.
Boggs said, "It was good for me to stay out there and take my lumps and get better."
METS 11, CARDINALS 1: The Cardinals could only split a four-game series with the Mets. They mustered only a sixth-inning run on 2B Adam Kennedy's double and two groundouts. RHP Mitchell Boggs gave up 11 runs in six innings and has a Busch Stadium ERA of 12.19 in his two starts there.
NOTES & QUOTES
--INF Aaron Miles singled in the third inning to run his hitting streak to a career-high 15 games, which also is the longest hitting streak by a Cardinal this season. Miles is hitting .400 (26-for-65) in the streak.
--C Yadier Molina ran his hitting streak to 10 games with a second-inning single. Molina, batting .303, has batted .351 in his streak.
--LF Chris Duncan singled to run his hitting streak to seven games and drove in the Cardinals' only run with an infield out.
--The Cardinals remained 2 1/2 games behind Chicago and two in front of third-place Milwaukee in the NL Central.
--1B Albert Pujols remained one home run short of 300 for his career and came out of the one-sided game after six innings.
BY THE NUMBERS: 19 -- Blown saves by the Cardinals' bullpen in their first 83 games. They had only 11 blown saves last year.
QUOTE TO NOTE: "It just wasn't going maybe as planned, so give this a shot." -- LHP Mark Mulder, on being activated from the disabled list as a reliever.