"Jeff had pretty much taken over from the defensive end" before Napoli went to the disabled list on July 6, manager Mike Scioscia said on Saturday. "He's been terrific. Jeff is still fresh. We're going to keep him in there as much as he can play."
Napoli played five innings on Friday night in the California League, going 1-for-2 with a single and walk. He is expected to serve as designated hitter today before resuming his catching duties with seven to nine innings, Scioscia said, on Sunday.
"Nap came out of the game great," Scioscia said. "He had good timing on his throws and everything went well.
"When Nap comes back, we're going to get both of them in there."
Ryan Budde has made one start, in Baltimore, since Napoli went on the disabled list. That happened to be the only game the Angels have lost among eight on the road trip through Baltimore, Boston and The Bronx going into Saturday's game against the Yankees.
The Angels are 45-20 with Mathis starting behind the plate. With Napoli, their record is 24-19. Those numbers are factored into Scioscia's evaluations along with catcher's ERA.
With the combined shutout of Ervin Santana and Francisco Rodriguez on Friday night, Mathis' ERA was shaved to 3.54 in 572 innings caught. Napoli's ERA, across 387 innings, is 4.33.
"The bottom line," Scioscia said, "would be wins and losses. As you break down ERA, individual matchups with pitchers, you get an idea who's performing better.
"When a guy catches, how many runs do you give up -- that's a big part of it. How your pitches perform, that's what that position is evaluated on."
Among current Angels pitchers, Santana, Joe Saunders, Jered Weaver, Scot Shields, Darren Oliver and Jose Arredondo have better ERAs with Mathis. Jon Garland, John Lackey, Darren O'Day, K-Rod and Justin Speier have done better with Napoli.
With Saunders -- 3.08 with Mathis, 3.11 with Napoli -- it's a virtual deadlock.
Mathis, whose start on Saturday was his 21st in the past 22 games, is batting .222 with a .374 slugging percentage and .303 on-base percentage. Napoli is batting .204 with .472 slugging and .308 on-base marks.
Power production has been exceptional by the Mathis-Napoli tandem. They have combined for 20 homers, 12 by Napoli, and 55 RBIs, 36 by Mathis. The club leaders, with 18 homers each, are Vladimir Guerrero and Torii Hunter. Mark Teixeira brought 20 homers over from Atlanta. Hunter's 59 RBIs lead Guerrero by one and Garret Anderson by two.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.