While trying to fill Doumit's big shoes, Jaramillo and Diaz have combined to hit .324 entering action on Wednesday night.
Diaz, 25, has started five straight games and has hit safely in six of his first seven starts, including his first career three-hit game on May 10.
"He puts the ball in play and has gotten some big hits for us," Pirates manager John Russell said. "If there's a guy who's swinging well, we've got to try to utilize him."
Jaramillo, 26, has gone 12-for-43 for a .279 average with seven doubles and five RBIs in 13 starts.
"We said it when they first came up -- when everybody was asking if we should go get a veteran catcher, I think I said back then and GM Neal Huntington said back then that you just don't go find a catcher," Russell explained. "It's not an easy position to fill, and we felt like we had two of the young catchers in the game right now who are pretty good.
"They were given the opportunity, and I think they took advantage of it, and I think we're seeing that we did have good options. Again, it's not Ryan Doumit, a four-hole hitter and the presence that Ryan brings on the club, but they've filled in very adequately, and I think even above some people's expectations. They've swung the bat, and they've caught very well. We felt very confident that these guys were very good catchers, and we've got two of the younger catchers in the game that we feel have a bright future. I think both of them do."
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.