It's baseball season. United Airlines will fly 13 teams this season.

If you watched Sunday night's Chicago Cubs versus St. Louis Cardinals game on ESPN - it was opening night of the 2015 baseball season -  you may have seen several advertisements for American Airlines, including one just behind the Cubs on-deck circle. 

You might think the Cubs fly American, right? But this is not the case. Even though American signed a huge sponsorship deal with the Cubs in the offseason, the Cubs continue to fly United Airlines. United had been a Cubs sponsor for the previous 10 years, according to Chicago Business Journal. 

As I understand, sponsorship and charter deals are signed separately. And around Major League Baseball, United handles a lot of charters. United has 13 teams this year, according to a recent note to the airline's employees. These are the teams:

  • Chicago Cubs
  • Chicago White Sox
  • Cincinnati Reds
  • Cleveland Indians
  • Houston Astros
  • Kansas City Royals
  • Los Angeles Angels of Anaheim
  • Los Angeles Dodgers
  • Milwaukee Brewers
  • Philadelphia Phillies
  • Pittsburgh Pirates
  • San Diego Padres
  • Washington Nationals.

You might think baseball players would get special interiors with big leather seats and wooden finishes. But United uses Boeing 737s, Airbus A319s and Airbus A320s for charters, and they are the same planes regular passengers fly on every day. Granted, they don't fly full, so players usually get their own rows. This is not a private jet-style experience. 

One major difference is catering. If you look carefully at the tweet below, you'll see a recent menu the New York Yankees had on one of their Delta Air Lines charters.