From BP, but not behind the paywall, a great article on some tendencies in strike zone variations and the value of catcher framing. It seems that umpires vary the strike zone a bit depending on how pitchers throw to different hitters, with one Ranger brought up as an example:
For example, Jason Kendall hangs over home plate and is among the batters with the highest hit-by-pitch rates. Nonetheless, his strike zone was shifted almost an inch inside relative to the average right-handed batter. On the other end of the spectrum, Nelson Cruz has a very upright stance that keeps him away from the plate, and he is near the low end on hit-by-pitch rates. However, his strike zone was shifted almost an inch outside relative to average. What could be causing this disparity?
You might know that Kendall displayed the last vestiges of a power stroke during final years of the Clinton administration, while Cruz had a slugging percentage of .555 over the last three years. Despite Kendal’s tendency to crowd the plate, pitchers are unafraid to come inside and over the plate to him, whereas low and away is the favorite spot for a hurler confronting Cruz.
The typical pitch location seen by the batter has a strong correlation to the horizontal shift in his strike zone. Batters who see more pitches on the outside edge also see their strike zone boundaries shift farther away on both the outside and inside edges of the plate. Batters who see more pitches on the inside edge see their strike zone boundaries shift toward the inside.
Perhaps not surprisingly, this jives with the theory that catchers and pitchers can influence the ump's zone if the pitcher is consistently hitting the catcher's target. The article found that Francisco Cervelli was able to coax a few more strike calls than Posada in games started by Vazquez.
The article also indicates that pitchers who throw more on the edges of the zone get a larger strike zone than pitchers who throw more strikes, but more strikes in the middle of the zone.
I suspect that most teams, including the Rangers, have some proprietary data on stuff like this. The Rangers place a high value on a catcher's work behind the plate (the stuff that fangraphs cannot measure and quantify) and this article shows why.
Some of this has been suggested and theorized for many years, but now the data is backing it up with details and nuances. There is a LOT more in the article, check it out.