The Seattle Sounders have USA captain Clint Dempsey, whom they brought back to MLS after six seasons in the EPL.
And before the 2014 season began, Toronto signed USA national team star Michael Bradley and England international Jermain Defoe, and brought in Brazil World Cup goal tender Julio Cesar on loan.
Yesterday, MLS expansion franchise NYC FC, which begins play in 2015, announced that its first player signing is Spain's David Villa, who this season helped Atletico Madrid win La Liga and reach the UEFA Champions League final.
Villa, who won a Champions League title with Barcelona, is Spain's all-time leading scorer, with 56 goals in 94 appearances. He was part of the 2008 European champions and 2010 World Cup champions and is on the roster for the 2014 World Cup.
The Union has, well, 2010 USA World Cup reserve midfielder Maurice Edu, plus Frenchman Vincent Nogueira and Argentine Cristian Madiana - neither of whom ever capped for their national teams.
It is safe to say the Union definitely lacks star appeal, and when a team has fewer points (14) than games played (15), fans can't help but wonder why they are getting mediocre hamburger while fans of other franchises get grain-fed rib-eye.
Major League Soccer clearly is becoming more of a viable destination spot for international players. But unlike in the old North American Soccer League, the foreign players coming to America are not just washed-up stars looking for a final payday based on their name recognition.
Call it the "David Beckham Legacy." When he joined the Galaxy from Real Madrid, he made it OK for players who still had enough game to stay in top European leagues to come to MLS instead.
The fact that current USA stars such as Bradley and Dempsey can return from Serie A and the EPL without hurting their national-team status also speaks to the growing quality of MLS.
So if I'm one of the 18,000 who loyally attend Union matches at PPL Park, I'm asking, how come New York, Los Angeles, Toronto and Seattle can get land high-profile game-changing players?
The Union has a strong and passionate fan base. PPL Park is one of the newest and top soccer-specific stadiums in the USA, and the match-day atmosphere rivals any in MLS.
I'll be honest and concede that Philadelphia does not have the international appeal of New York, Los Angeles or perhaps even Toronto, but it's not Salt Lake City or Kansas City.
People around the world recognize Philadelphia as a top U.S. city. All of the selling points appear to be in place for the Union to be a destination franchise, except for one - the money.
You have to pay to convince a player who can still compete in a top league in Europe to come to MLS. You have to give him a salary slightly better than what he could have reasonably expected to get elsewhere.
Defoe and Bradley are guaranteed more than $6 million in base compensation this season. Dempsey, Keane and Donovan will get more than $4 million. Villa will reportedly earn more than $4 million a season for NYC FC.
Whether Union management wants to concede the point or not, a Philadelphia franchise is considered "big market" in any professional sport.
Fans expect that it will roll financially with the big dogs.
The Union ($3.92 million) has the ninth-highest player payroll in MLS but that is right in the middle of MLS, and only about $700,000 more than Houston Dynamo at 16th.
The Union doesn't have pockets as deep as New York, Toronto, Los Angeles and Seattle, but it can't operate as if it's the Vancouver Whitecaps or Columbus Crew, either.
There is a balance that can be reached. The price of doing business doesn't have to be jaw-dropping high.
Only 12 MLS players make at least $1 million in base salary. The Union's highest-paid player is Edu, who makes $650,000 on loan from Stoke City. But Edu is a midfielder, and midfielders need a quality finisher up front to impact a game.
Strikers are the true game-changers. There is a reason why 11 of the 16 highest-paid players in MLS are forwards.
Despite 5 years of failure to do so, the Union must try again to acquire a reliable scorer. The thing is, it can be done without breaking the bank.
The Red Bulls signed MLS leading goal scorer Bradley Wright-Phillips (11 goals) from Brentford of England's League One during last summer's transfer window. His salary is $372,500 this season.
Forwards such as Wright-Phillips, ones who are on the fringes of the top European Leagues but could have real impact in MLS, are out there during the summer transfer window.
And it is no longer unreasonable to think they will come across the pond.
The Union just has to be willing to make a withdrawal, because all of the other selling points are already in place in Philadelphia.