Neither team seemed worried that some of the premium seats — any seat that comes with an amenity, like waiter service or access to a dining club — were unfilled. Some of them could have owners who simply did not show up, which hurts food, parking and merchandise sales. Other seats may be part of partial season ticket plans that did not include games played last week.

“If someone’s not there at the moment, that doesn’t mean it’s unsold,” said Dave Howard, the vice president for operations for the Mets. So far, he said, fans are spending about 60 percent more on food, beverages and merchandise than they did at Shea Stadium. “There’s a lot of circulation in the ballpark.”

Many fans with tickets are trying to recoup what they can by selling some of them online well below face value. More than 10,000 tickets (about 20 percent of the ballpark) for the Yankees’ game against the Oakland Athletics on Wednesday were available, a handful for as little as $5, according to FanSnap.com, which scans the Web sites of five dozen ticket resellers.

“More season-ticket holders than ever before are selling into the market,” said Michael Janes, FanSnap’s chief executive. “Some people need to generate cash to pay the rent.”

The teams’ sluggish starts on the field — including the Yankees’ 22-4 loss Saturday to the Cleveland Indians — have not helped generate extra buzz. Attendance across the major leagues has dipped this season, and plenty of premium seats are empty in other ballparks. Many basketball and hockey teams have also had attendance declines.

But the slow start in New York is striking considering how much the teams here spent to build and promote their parks. Like airlines that break even on economy tickets and rely on first-class travelers to turn a profit, the teams need to sell their most exclusive seats to help repay the hundreds of millions of dollars of tax-free bonds they issued to finance their new parks.

The unfilled seats in New York are even more glaring compared with how robust sales have been for previous stadium openings. The Baltimore Orioles sold out 67 of their 80 home dates in 1992, when Camden Yards opened. The Cleveland Indians sold out 36 games in the strike-shortened season in 1994, and were filled to capacity 455 consecutive games from 1995 to 2001.

Slideshow   Fans' view of opener at Mets new Citi Field Lifelong Mets fan Matt Casey gives his unique tour of the new stadium in Queens.

After moving to their new park in 2001, the Houston Astros drew 3.1 million fans, 300,000 more than they ever attracted at the far larger Astrodome. The Pittsburgh Pirates, a perennial second-division team, sold 2.4 million tickets in 2001 when PNC Park opened, 700,000 more than they ever sold at Three Rivers Stadium.

Mets officials say they are encouraged that they have already sold the equivalent of 25,000 full season tickets, 7 percent more than in 2008. Most of the team’s 15-game plans are sold out, and single-game ticket sales for April and May are 87 percent higher than in the same period last year.

Randy Levine, the Yankees’ president, said last week that attendance at the second home game was proportionately ahead of last year’s pace. Levine also said that 80 to 85 percent of the Stadium’s 4,000 premium seats had been sold for the full season.

For next season, the Yankees plan to raise premium ticket prices 4 percent.

This article, "Is This Seat Taken? In Front Rows of New Ballparks, No" originally appeared at The New York Times.

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