Perez started 158 games last season, including the playoffs, which was a Major League record for catchers. And while manager Ned Yost has pondered ways to get Perez rest this season, Perez started the first six games.
And Perez may not get a game day off until at least later in the week. The team is winning, Perez is playing at a high level, and he doesn't want time off, thus making Yost's commitment to getting Perez rest all the more difficult.
"It's just tough," Yost said.
Meanwhile, backup catcher Erik Kratz sits and waits, while trying to stay sharp mentally for that time when he will get the call.
"You have to try to treat your pregame practice as if it were game situations," Kratz said. "Like when I catch bullpen [sessions], I get in full gear and pretend it's a game situation. Plus I prepare every day as if I was starting."
Kratz also stays in close contact with all the pitchers.
"It's important to establish that trust with them," Kratz said. "You don't want them to feel any different just because you're starting and not Salvy."
That, in Kratz's mind, is the key -- developing trust with the players and the coaching staff so that when he gets the call, everyone believes it's a safe choice.
"You don't want anyone to think there's a huge dropoff when Salvy isn't in there," Kratz said. "I know why he must play -- he's an All-Star, a Gold Glover, a huge part of this team. But I have to do my best to contribute when I get in there. Everyone has a role on this team and that's got to be my role."
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.