Diamondbacks’ Pitching Strikes Gold With Carbon-Copy Catchers

PHILADELPHIA — Sometimes the catcher for the surging Arizona Diamondbacks is a 34-year-old veteran of four teams with a low batting average, a bargain contract and a deep commitment to helping his pitchers. Other times, he is a different catcher who meets those same criteria.

But there is one big difference between the Arizona catchers Chris Iannetta and Jeff Mathis: Iannetta had 10 years 13 days of major league service before this season, while Mathis had 10 years 12 days.

Consider Iannetta to be Mathis’s firstborn twin. Neither has ever amassed 350 at-bats in a major league season, and neither is the starter now. They share time with yet another catcher — Chris Herrmann, who is younger and…