Moustakas connected in the seventh inning on right-hander David Pauley's first pitch. He sent a rocket screaming over the center-field wall for the appraisal of the 17,127 in-house judges.
"That was our first grand slam of the year and it came at a great time," manager Ned Yost said.
The five-run inning began against left-hander Ricky Romero, who came into the game with a glossy 8-2 record.
"This sport we play works in mysterious ways sometimes," Romero said. "You can be on top of the world one day and the next day you're trying to find yourself, and that's what I feel like right now. You feel like you're in quicksand, and every time you just keep getting deeper and deeper and you don't know how to get out of it."
After Alcides Escobar's walk and Eric Hosmer's double, Pauley relieved Romero, plunked Billy Butler and surrendered an RBI single to Yuniesky Betancourt.
Up came Moose.
Pauley's next pitch prompted either calls of the wild or howls of dismay around Toronto Bay. Hard to tell which but, come to think of it, this is a country where the moose is celebrated.
Moustakas must have felt he pulled himself out of some quicksand with his five-RBI game. When he knocked an RBI double in the third, he snapped a 0-for-15 skid that had left him hitless over the weekend at Minnesota. In fact, Moustakas sat out Sunday's game, a third straight loss to the Twins, after a doubleheader sweep on Saturday.
"Two bad days and we've just got to be able to put those days behind us," Moustakas said. "Those days in Minnesota were real bad but that's what makes great teams great, being able to put the ones behind and building off today and working toward tomorrow."
Teaford managed to escape a first-inning jam with just one run scoring.
"Normally I'm not very good in the first inning but, luckily, I was able to keep the damage to one -- I had the bases loaded, one out and I was able to manage on that one but when you get 11 runs, it's easy to pitch," Teaford said.
The first two runs came in the second inning when his catcher, Salvador Perez, followed a walk by launching a two-run homer over the left-field wall against Romero.
"He hit it so hard on the line, I didn't think it had enough height to get out, but it got out and that was huge. It did turn the momentum around," Yost said.
After the first inning, the only interruptions to Teaford's smooth flow were solo home runs by Jose Bautista, his Major League-leading 27th, and by Colby Rasmus, a soaring shot to the Rogers Centre's top deck just inside the right-field pole. Was that ball still on the rise or had it lost altitude before hitting the façade on the fifth level?
"We'll have to check air traffic control to see if the ball was landing or not," Teaford said.
Teaford could afford to joke around a bit because he'd given up just five hits and two walks in notching his third career victory. He also virtually assured himself of another start in the last game before the All-Star break on Sunday at Detroit.
Meanwhile, Moustakas could savor his 14th home run and his first slam that gave the Royals a runaway victory.
"It was really cool," Moustakas said. "I got a good pitch to hit, fastball in the middle of the plate and just tried not to do too much with it, tried to get the guy in from third and I was fortunate enough it carried out of the yard."
Tried not to do too much with it? Looked like he did quite a bit with it as it screamed over the center fielder's head.
"I hit it pretty good," Moustakas conceded, laughing.