Psyonix sent out the following

 Psyonix, independent video game developer and publisher, in partnership with Major League Baseball, has revealed the MLB Fan Pack DLC for Rocket League! With the new pack, players will be able to rep their favorite team with a variety of MLB-themed cosmetic items beginning March 25 on all platforms for $2.99 USD (or regional equivalent).

The MLB Fan Pack includes:

  • Player Banners, Flags, and baseball cap Toppers for all 30 teams

  • MLB-branded Flag and Player Banner

  • A baseball-themed Rocket Boost

This is indeed a nice touch