Mathis began to notice the difference while working with Don Wakamatsu, who was the bench coach for Toronto.
"It was fun getting back together and working with him again," Mathis said. "He worked with me letting the ball travel and get to me and [then] loading. It took a lot of stress off my arm, and made me feel a lot more accurate."
"I wasn't maximizing everything I could. At times I tried to do too much and throw every guy out, and in reality you can't. Sometimes the base is stolen off the pitcher. You just have to stay within yourself and try to make a good accurate throw."
That success has transferred over in Miami. Over 10 starts, the 30-year-old has thrown out 80 percent (8-of-10) of runners trying to steal. If he had enough appearances to qualify, he would lead all Major League catchers.
Rob Brantly and Miguel Olivo have caught another 16 runners -- on 47 chances -- for a 34 percent clip.
"I think everyone as a whole is throwing the ball really well," Mathis said. "That's a tribute to the pitchers, too. Giving us a chance, mixing up their looks."
Christina De Nicola is a contributor to MLB.com. Joe Morgan is an associate reporter for MLB.com.