Martin Maldonado has been a very good defensive catcher in his career
The Houston Astros didn't care whether Maldonado hit well or not. They had Jose Altuve, Alex Bregman, Kyle Tucker, and Yordan Alvarez to take care of that part of the game.
It showed in his stats, too. In 2023, Maldonado slashed .191/.258/.348/ for an OPS of .606. He hit 15 home runs and had 36 RBIs with 33 runs scored. The home run total isn't bad for 116 games played but the other numbers are below average.
The reason he is an everyday Major League player is his glove. His offensive stats were that bad in 2023 and he was still a plus WAR player.
With how bad it was last year with Yasmani Grandal and Seby Zavala, this is a major upgrade. Stolen bases, past balls, and plays at the plate are all going to be better for the White Sox with an actual catcher.
With improved defense at catcher, it might help the rest of the team as well. As mentioned before, there is improved defense coming in on all fronts and Maldonado is at the top of it all.