"The kid always hits," said Jays manager John Gibbons, referring to Diaz. "He's a good hitter."
In 11 games with Triple-A Syracuse this season, the 24-year-old Diaz hit .368 (14-for-38), with one home run and seven RBIs. Over seven Minor League seasons, the 5-foot-11, 180-pound catcher owns a .307 batting average.
With an open roster spot due to Thomas' departure, the Jays opted to call up Diaz, whom they believe is deserving of the opportunity.
"He's been swinging the bat really well," Jays general manager J.P. Ricciardi said. "He swung the bat well for us the last few years, and this gives us the chance to bring another bat here. He's deserving of being up here."
Ricciardi also noted that Diaz gives the team versatility, as the catcher is also able to play a little third base, as well as be used in pinch-hit situations. There is a possibility that he could even fill in on occasion as the DH.
"He throws well," Ricciardi said. "Diaz is getting better and better each year. He's got good hands, and he's a very athletic kid. Like I said, he's deserving of being up here and we're excited for him."
Diaz was not in the lineup for Monday's series finale against the Tigers, but he was available to come off the bench.
"I feel excited," Diaz said, after taking his first batting practice with Toronto. "Just how everybody feels when they get called up, it's great."
David Singh is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.