The Angels wiped out a 7-5 Royals lead in the eighth inning. Mark Trumbo singled between two outs against reliever Aaron Crow and when switch-hitter Kendrys Morales came out as a pinch-hitter, the Royals replaced Crow with left-hander Tim Collins.
Morales bashed Collins' first pitch, a fastball, over the left-field wall for a two-run homer and a 7-7 tie.
"Morales is a much better left-handed hitter than right-handed hitter so when I saw him in the back of the dugout with his helmet on, I knew they were going to pinch-hit him in that situation," Yost said. "We had Timmy ready. Big power hitters like Morales come off the bench hunting a fastball and Timmy threw him a fastball. It was definitely in a good spot for him to hit it and he hit it a long way."
This season, Morales had hit right-handers at a .290 pace but was just .209 against lefties. He'd never faced Collins before.
"I just made a working mistake," Collins said. "I just went out there and gave him exactly what he wanted. As a pinch-hitter, you're coming off the bench looking for a fastball and that's it and I gave it to him. You see the results."
Morales seemed somewhat bemused that the Royals thought they'd have an advantage when he swings from the right side.
"Just let them think it's still the weakest swing that I've got," he said.
The Angels then loaded the bases as Mike Trout and Erick Aybar each singled, and Albert Pujols was hit by a pitch. Jeremy Jeffress relieved Collins and walked Torii Hunter to force in the go-ahead run.
An insurance run was added in the ninth after just-arrived Royals center fielder Jason Bourgeois ran down Vernon Wells' long drive but dropped it. Bourgeois was charged with an error as Wells got to third base, later scoring on a groundout.
"Bourgeois ran about a mile-and-a-half to catch that ball, so he gave it a great effort. He just couldn't hang onto it," Yost said.
Butler finally unloaded No. 100, smacking a 404-foot drive over the left-field bullpen off left-hander C.J. Wilson as the second inning began. The milestone blast ended a homer-less span of 92 at-bats for Butler. He had not connected since Aug. 11 at Baltimore.
"I'm glad I did it at home. It was a good feeling," Butler said. "I got a pitch to drive, got a good piece of it and knew it was gone."
Fans marked the occasion by cheering until Butler made a curtain call, bouncing up the dugout steps to wave his helmet to the crowd.
"I was glad to do it in front of the home crowd and the reception was great," he said.
Butler has a history of milestones against the Angels -- his first Major League hit and his first home run in 2007 and his 500th hit in 2010 all came versus L.A. Now it's his 100th homer.
It was also Butler's 26th homer this season. Almost immediately, Mike Moustakas became the second Royal to join the 20 club.
After an out, Moustakas hit a line drive that carried just over the right-center field wall. He's the first Royals third baseman to hit the 20 mark since Dean Palmer in 1998. Of Palmer's 34 homers that year, 26 came as a third sacker.
Jeff Francoeur provided the Royals' third homer, a two-run shot off Garrett Richards in the sixth inning for a 6-4 lead in a ballpark not conducive to homers.
"You've got to earn them to hit them here, at night especially," Angels manager Mike Scioscia said. "Sometimes during day games, we've been here, you get a little breeze, the ball carries better. Center field is like the Grand Canyon here. It's big, a lot of room, and it's really tough to hit them out there."
Then, in the top of the seventh, Francoeur made a defensive play that enabled the Royals to keep a 6-5 lead. With two runners on, he grabbed Aybar's double and his quick, strong throw toward home kept the second runner from scoring.
"He made the play of the game on Aybar's double down the line to hold Trout from scoring," Yost said. "At that point it was huge because Louis Coleman struck out Hunter and [Howie] Kendrick to keep the one-run lead. I thought that was a phenomenal play."
Yet, when the 3-hour 42-minute marathon was over, what seemed like a party when Butler popped the cork had turned flat.