"I was not prepared for that game, and it clearly showed out there," Bannister said. "I didn't give us a chance to win. I got exactly what I deserved and I take all the blame."
Pena, making his first start of the year, tried to take the heat off his pitcher.
"I have to do a better job calling games," Pena said. "It's my fault. I let my team down and I really feel bad for it. I apologize to my teammates and I apologize to my team."
Travis Snider also homered to help the Blue Jays snap a three-game losing streak and win for the 18th time in 22 home games against Kansas City.
Bautista hit a three-run drive off the facing of the third deck in left in the fifth, then added a two-run drive to left in the seventh, the third multihomer game of his career. His five RBIs matched a career high.
Attendance was 10,314, the smallest crowd in the 22-year history of Rogers Centre and breaking the mark set last Wednesday, when Toronto drew 10,610 for a game against the Chicago White Sox.
Morrow (1-1) allowed one run and three hits, lowering his ERA from 12.00 to 7.31. He walked two and struck out eight.
"He was good; Morrow was really good," Royals manager Trey Hillman said. "He made it hard on us. He located his breaking ball down and out of the zone, and he threw it for strikes."
Tagged for seven runs and eight hits in his last start, Morrow found success in this one by lowering his arm angle on the advice of pitching coach Bruce Walton.
"You guys probably couldn't even tell, but to me it feels like I'm throwing sidearm," Morrow said. "It's really not much at all; it's just getting my upper body more up and down rather than tilting off to the side."
The right-hander held the Royals without a hit through the first five innings but lost his shutout in the sixth.
Alex Gordon drew a leadoff walk, took second on a grounder and went to third when ninth hitter Yuniesky Betancourt lined a single through the left side. David DeJesus followed with an RBI single to right.
Bannister (0-1) allowed six runs and seven hits in 5 1/3 innings, raising his ERA from 2.19 to 4.58. He walked four and struck out six. He acknowledged being so angry that he didn't stay in the dugout after being pulled, but otherwise declined to elaborate on his lack of preparation.
"The game needed to be planned for better," Bannister said. "They're a good team, a good hitting team, and it was a very subpar effort out there. I take all the blame for it. It wasn't how I wanted to go out there and pitch."
Bannister spoke briefly with Pena on his way out of the clubhouse, and the two exchanged a fist-bump before Bannister left.
"I don't blame him; I blame myself," Pena said. "It's my fault, and I should have called a better game. He's taking responsibility because he's a good teammate, but I have to do a better job."
Toronto opened the scoring on an odd play in the third. One out after Mike McCoy singled and stole second, Alex Gonzalez struck out on a wild pitch that bounced away from catcher Brayan Pena. Rather than allowing the ball to roll into the first-base dugout, which would have kept McCoy at third, Pena threw to first, and Gonzalez was safe when Pena's high toss pulled Billy Butler off the bag. McCoy never broke stride and scored without a throw.
"He should have let it go in the dugout," Hillman said. "Then you end up with first and third. That's tough. Brayan thinks he's got a play at first base. For a second it looked like he was going to have a play and then obviously he didn't. Heads up baserunning by McCoy."
Snider made it 2-0 with a leadoff homer to right in the fourth before Bautista's three-run shot made it 5-0.
Gonzalez hit an RBI double in the sixth and Bautista capped his night by homering again in the seventh.
Toronto first baseman Lyle Overbay, who came in batting .080, went 2-for-2 with two walks and scored twice, raising his average to .115. He also reached on a catcher's interference call.
Royals OF Scott Podsednik, who leads the AL with a .457 average, went home to Kansas City to deal with a family emergency and should rejoin the team Tuesday, Hillman said. ... Toronto LHP Brian Tallet (sore forearm) will have his next start pushed back three days. Tallet had been set to pitch Friday at Tampa Bay but will not work until Monday at home against Boston. ... McCoy's three hits were a career high. ... Blue Jays 3B Edwin Encarnacion (sore right arm) missed his fifth straight game.