Mathis, who has caught 18 of Santana's 24 starts this season, was replaced by Mike Napoli.
"Mathis is feeling OK but not at the level he needs right now," Angels manager Mike Scioscia said.
Mathis has become somewhat of a personal catcher for Santana the past two years by catching 45 of his past 56 starts, but Napoli is no stranger to catching Santana as he's done it five times this season and 31 times in his career. But the main difference is that this year Santana has a 7.99 ERA when Napoli catches him and a 4.93 ERA when Mathis is behind the plate.
But Scioscia was quick to note that Napoli caught Santana earlier in the season when the right-hander was still battling elbow problems that sidelined him nearly two months into the season.
"He caught him in some games earlier this season back when Ervin's stuff wasn't totally crisp, so the small sample is a little skewed," Scioscia said.
Napoli, though, will bring power to the lineup as he hit his 19th home run of the season Sunday, which also was his 62nd career shot. That broke the club record for home runs by a catcher that was previously held by Bengie Molina and Lance Parrish.
Mathis isn't as good at the plate (.211 batting average this year) but is regarded as the better defensive catcher even though Scioscia said Napoli has been getting better recently.
"I think on the defensive end our catchers have done an outstanding job," Scioscia said. "I think Mike Napoli over the last 10 games has done very well defensively and Jeff has done it all season."
So with Mathis' defense and Napoli's offense, Scioscia likes what he's been seeing this year from his catchers yet again even though he said they both could improve on their weaknesses.
"You can point to little deficiencies and say Jeff needs to bring a little more offense and Mike needs to bring a little more defense but those guys have both been terrific," Scioscia said. "If you look at what they've done on a statistical basis then they're ranking up there with some of the top catchers in our league."
Rhett Bollinger is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.