A switch-hitter, Bonifacio has hit right-handers at a .275 rate in his career compared to .255 against left-handers.
Bonifacio hit just .218 this year for Toronto although he's batted .273 over the last two months.
"I don't want to make an excuse, but I got hurt in May last year and I didn't play much until I got to Spring Training, so I think it took my timing a little while to get back," Bonifacio said.
He came from a Blue Jays team that was last in the American League East to a Royals team that still has postseason hopes.
"I was excited because I came to a team that was in the race for the playoffs," he said. "And I wasn't getting much playing time over there, so maybe here I can play more and help them out."
Bonifacio wore uniform No. 1 for Toronto, but that's assigned to Jarrod Dyson on the Royals so he had to pick another number. His choice gave him the highest number on the roster: 64.
"They told me the numbers they had available and I asked for it because it's the one I wear in the Dominican in winter ball," he said. "So even my little brother talked to me yesterday and said, 'Wear 64,' so I just decided to do it."
His brother is Jorge Bonifacio, a highly-regarded outfielder and the Royals' No. 5 prospect according to MLB.com who is with Double-A Northwest Arkansas.
"He called me right away, he was really excited," Emilio said.
Bonifacio singled in his first Royals at-bat in the 4-1 loss to the Tigers and performed well at third.
"I was really impressed," Yost said. "I thought he did a good job of playing third base -- a very nice, athletic third base. Swung the bat very well, got a base hit and smoked that last ball to the shortstop for an out. I was pleased with him."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.