"I wouldn't call him the backup," said Gaston, referring to Zaun. "I would say that Barajas is going to catch a little more at this point in time. ... We'll give him a rest here and there, and Zaun will catch then.
"And if Zaun takes off, hey, it might switch back the other way. I'm just trying to put the best team out there."
Under Gaston's watch, Barajas has garnered 14 starts at catcher, compared to 10 for Zaun. But the 37-year-old Zaun has only started five of Toronto's past 17 games, dating back to June 28.
Neither catcher has excelled offensively since Gaston's arrival. With Gaston at the helm, Barajas has hit .180 (11-for-61) with three home runs and eight RBIs over 16 games entering Sunday. Zaun managed a .143 (5-for-35) average with one homer and six RBIs over 13 games during that stretch.
"He gives us a little more power," Gaston said of Barajas. "He's just played better. He's certainly had the better year back there, so far."
The 32-year-old Barajas has hit .256 with eight homers, 13 doubles, 29 RBIs and a .442 slugging percentage through 62 games this year. Zaun has hit .244 with five homers, seven doubles, 19 RBIs and a .375 slugging percentage in 57 games.
Zaun does boast a better on-base percentage (.354) than Barajas (.305), but that's one of the only areas in which he leads his counterpart. Entering Sunday, Toronto's pitching staff had posted a 3.48 ERA with Barajas behind the plate, compared to a 3.88 ERA with Zaun.
Barajas has also displayed a better throwing arm, nabbing 34.2 percent of would-be basestealers. Zaun, who missed 16 games in May and June with a right elbow injury between, had thrown runners out at a 26.3 rate. Barajas also performed well as the starter during Zaun's stint on the disabled list, hitting .298.
Gaston said he made a point of discussing the situation with Zaun, who is in the final season of a two-year, $7.25 million contract. Gaston told Zaun that the catcher still has time to regain the starter's role.
"I said, 'Hey, go take it back,'" Gaston said. "A lot of managers I've played for said, 'I never write up the lineup. You write it up.' I don't like using that, but there's a lot of sense to that, too. There's a lot of truth to that. I might put it down, but you certainly have something to do with it by the way you play."
It's a situation that could also play a role in Toronto's offseason plans. The Blue Jays are likely to bring back only one of Zaun and Barajas next season. The odds seem to favor Barajas, who is under contract for $1.2 million and has a $2.5 million club option for 2009.