What is the "X" MLB is teasing?

 

Are you ready? Set an alarm.

Something big is on its way Wednesday. pic.twitter.com/ps278EI9gz

— MLB (@MLB) March 28, 2022

X. What is MLB teasing here? Some folks think its the name of the MLB stuff that is going to be on Apple TV. Me? No freakin' idea. Am I ready? Wait. Is this DX from the WWE? I am so confused about this.