Don't know if they use any tech assisted umpiring in Baseball or not but in Cricket it's used a lot these days. And I can confirm that this has positively impacted decision making in games of Cricket.
The Decision Review System (DRS), formerly known as the Umpire Decision Review System (UDRS), is a technology-based system used in cricket to assist the match officials in their decision-making. On-field umpires may choose to consult with the third umpire (known as an Umpire Review), and players may request that the third umpire consider a decision of the on-field umpires (known as a Player Review).
But these decisions can often be wrong as well.