This was Torrealba's first year as a starting catcher. He posted a .236 EQA for the Rockies this year, after posting a .237 EQA for them last year (in a part-time role), and is considered a good game-caller.
Gerald Laird is still three years away from free agency, will probably make a total of $5 million over the next three years, and is considered a quality defensive catcher whose game-calling isn't a strength. He had a .217 EQA last year, after putting up a .263 EQA the year before.
Torrealba is probably about the same quality of catcher Laird is (well, I think Laird is probably better, because I think he's a better hitter than he showed last year, but anyway...).
The amount of interest shown by teams in someone like Torrealba, and the amount of money teams are willing to pay, is a very good indicator for the value Laird has, should the Rangers wish to trade him.