But the 29-year-old has flashed a hot bat of late.
On Friday at Rogers Centre, Mathis knocked a three-run double in a four-run fourth inning to help the Blue Jays beat the Detroit Tigers 8-3.
Carlos Villanueva won his fourth consecutive start to improve to 6-0.
Mathis extended his hitting streak to eight games with the bases-loaded two-out double against Rick Porcello (7-6). The career .199 hitter is batting .264 with five homers and 13 RBIs so far this season.
"We acquired [Mathis] as a top defender but when he got him in spring training we felt there was no reason why he couldn’t be more of an offensive player," said manager John Farrell.
Mathis — the Jays' starting catcher since J.P Arencibia went down with a broken hand Wednesday — has been working with hitting coach Dwayne Murphy at opening his stance so that he has a better view of the ball.
"I’m starting to feel more comfortable at the plate," Mathis said. "Just seeing some pitches better, having better at-bats and getting myself in better counts.
"And any time you can get in there, get reps, and at-bats you can get in a rhythm ... I’m looking forward to this run of getting to play a little bit more."
Travis Snider hit a two-run home run in the eighth against Duane Below to put the game out of reach. It was Snider's third homer since being recalled from triple-A Las Vegas on July 20.
It was the second win in a row for the Blue Jays (50-49) and the second loss in a row for the Tigers (53-47), who are second in the AL Central.
Villanueva gave up first-inning homers to Miguel Cabrera and Prince Fielder but did not surrender another run in his five innings.
After allowing four hits, two walks and two runs while striking out three, Villanueva is 4-0 with a 2.54 earned-run average in his five starts this season after beginning the season in the bullpen.
Mathis said Villanueva didn't make any major adjustments after the first inning, but that he started getting ahead of batters early in the count.
Farrell was impressed with how Villanueva settled down after a rocky first inning.
"We know what we have in him in terms of durability and number of pitches he can throw on a given night," said Farrell. "But he sets the tone, he throws strikes and is capable of making the key pitch in tough situations."
Meanwhile, Detroit's Porcello allowed six hits, two walks and five runs and struck out one in six innings.
In the top of the first, the Tigers struck quickly in a three-pitch span with two out as Cabrera and Fielder homered for a 2-0 lead. It was the 25th of the season for Cabrera and the 16th for Fielder.
The Blue Jays got one back in the bottom of the frame when Omar Vizquel doubled with one out and Edwin Encarnacion singled with two out.
The Tigers still led 2-1 in the fourth before the Blue Jays rallied for four runs.
With Encarnacion on first, Kelly Johnson walked with one out and Snider did the same with two out to fill the bases. Mathis sent everyone home with a double just beyond the reach of left fielder Quintin Berry.
Mathis said he was looking "just to get a pitch up in the zone that I could handle.
"Snider had a great at-bat in front of me to get on," he said. "(Porcello) hung a slider and I got decent wood on it."
Porcello said he simply didn't make a good pitch to Mathis.
"That ended up being the difference. That really is the summary of the game for me, that one stretch of three or four hitters," Porcello said. "I don't really care what happened the rest of the game. That was a three-run pitch right there."
"He was one pitch away from getting out of that inning and he hung a slider to Mathis that cleared the bases," Tigers manager Jim Leyland said.
Anthony Gose then singled on a grounder to first that Fielder couldn't handle and Mathis scored.
In the seventh, Canadian Brett Lawrie and Vizquel hit consecutive triples against Octavio Dotel to extend Toronto's lead.
Blue Jays relievers Aaron Loup and Brandon Lyon held off the Tigers through the seventh. But Cabrera opened the eighth with a double against left-hander Darren Oliver and slid safely home on a single to centre by Fielder. Blue Jays manager John Farrell argued the call at the plate.
Oliver retired the next three batters, two on strikeouts.
Snider's eighth-inning home run came after Tigers second baseman Omar Infante was charged with an error on a grounder by Yan Gomes.
Casey Janssen pitched the ninth for Toronto.
Notes: Attendance at Rogers Centre was 33,962. ... Adam Lind and Yunel Escobar were both scratched from Friday's game with back tightness. Escobar missed his third consecutive game. ...Drew Hutchison played catch on Friday, making 30 throws from 45 feet. He had not thrown since June 15 when he came out of his start with a sprained elbow ligament.