Since his joining the New York Red Bulls three years ago, Thierry Henry has never won Major League Soccer's most valuable player award. He has never finished as the league's top goal scorer or led the league in assists. He has won just a single playoff series, has never taken his team past the Eastern Conference semifinals and has unequivocally failed to end the franchise's 17-year championship drought.

But for most of his time in the MLS, Henry has held one specific distinction: He has been—by some distance—the league's most lavishly paid star.

In his third full season, Thierry Henry has already collected more than $21 million from the Red Bulls. Getty Images

In his third full season, Henry, 35, has already collected more than $21 million from the Red Bulls, and his guaranteed salary of $4.35 million for the current season makes him the highest-paid player in the league for the second successive year.

To put that figure in context, Henry's annual paycheck isn't merely bigger than any of the league's other 556 players. It exceeds the total payroll of D.C. United, the Houston Dynamo, the New England Revolution and a dozen more of the league's 19 teams.

All of which raises a rather awkward question about someone who may be the most accomplished player to dabble in U.S. professional soccer since Pele: Is he actually worth the money?

"It's so difficult to quantify," said Alejandro Moreno, a former MLS Cup winner with Columbus and now a soccer analyst. "Is he a difference maker for the team, is he an impactful and influential player in MLS? Clearly, the answer is yes. But when you make that kind of investment, you have to believe it's to win a title."

By that standard, the Red Bulls' splashy acquisition of Henry counts as a miss. The team currently occupies first place in the Eastern Conference ahead of Sunday's marquee home matchup with the Los Angeles Galaxy (1 p.m., ESPN2), but as their long-suffering fans know only too well, New York remains the league's only original franchise without a major trophy.

But Red Bulls coaches, team officials and league executives take a different view. Since he joined the franchise on a 4 1/2-year contract from FC Barcelona in July 2010, Henry has been almost everything they hoped for.

"Without a doubt, he has delivered," said Red Bulls general manager Jerome de Bontin. "He has demonstrated on the field since he got here an extraordinary ability to bring the game to a level that is only played by the top athletes."

The numbers tell the story rather starkly. In 2009, the season before Henry joined the team, the Red Bulls posted a league-worst record of 5-19-6, earning 0.70 points per game on average. Since he signed, the club has a 39-24-32 record, averaging 1.57 points per game, and has qualified for the playoffs every season.

Red Bulls executives say the team's turnaround is down to Henry's competitive drive, his ability to elevate the play of his teammates, and the sense of professionalism he has helped instill at the perennially underachieving franchise.

But mostly, it's down to his goals. Since his MLS debut midway through the 2010 season, Henry has scored 36 goals in 79 games, the second-highest tally in the league in that span behind San Jose striker Chris Wondolowski's 60 goals. He also has 20 assists and has been named Player of the Week more often than anyone else.

"A lot of teams in MLS are hard-working and organized, but what they don't have is firepower," says Andy Roxburgh, the Red Bulls sporting director. "That is what Thierry brings us."

In truth, Henry's value to the Red Bulls comes not just from the fact he's such a remarkable goalscorer, but that he's also a scorer of such remarkable goals.

In the past three years, Henry has scored memorable solo goals, spectacular free-kicks and even directly from a corner. Only last week, he all but locked up the MLS Goal of the Season award with an acrobatic bicycle kick against Montreal.

For De Bontin, the team's general manager, that goal encapsulated Henry's singular worth not simply because it came in the 88th minute and won the game, but rather on a Wednesday night that featured a full slate of NBA and NHL playoff games, the goal occupied the No. 1 spot on ESPN SportsCenter's Top-10 plays.

"Those are things that you can't invent—even if you were trying to make them happen, you could not with out the talent of a player like Thierry," he said, adding that Henry's fireworks are the team's most powerful marketing tool.

Likewise, the team says that Henry, who won a World Cup with France and scored 175 goals for Arsenal in the English Premier League, has a world-class pedigree that has helped sell tickets, attract new players and bring both the club and the league a level of credibility that few other players on the planet could provide.

But those attributes are tough to quantify by traditional measures. In fact, crowd numbers at the 25,000-seat Red Bull Arena have dropped every year since Henry joined the club. Average attendance last season fell to 18,281, representing a 7% drop from 2011. Through five games this season, the Red Bulls are averaging 16,021.

Still, De Bontin says Henry's offensive prowess and global appeal of Henry have enhanced the team's international standing as well as the brand of beverage maker Red Bull, which bought the club in 2006 and also owns teams in Austria, Brazil and Germany.

"Often some comparisons are made with David Beckham, and in his own right David brought a lot of exposure to the league," he said. "But in terms of performance on the field and past success, David Beckham never played in a World Cup final, let alone won one. If you look at Thierry's record, he has won everything."

But for some observers, Henry won't really be able to justify his astronomical salary until he emulates Beckham by adding one final trophy to his glittering résumé.

"I think for any of these big-time, big-name, highly-paid players, the final barometer is whether they can win a championship," said Moreno. "David Beckham was able to do so and now that Thierry Henry is the league's highest paid player, he needs to take that next step and win a championship for that organization."

Write to Jonathan Clegg at jonathan.clegg@wsj.com

Corrections & Amplifications

The New York Red Bulls are the only original franchise in Major League Soccer yet to win one of the two major titles, the MLS championship or the Open Cup. An earlier version of this article incorrectly said New York was the only original franchise yet to win an MLS championship.