"We all know the home run is the toughest thing to do in our game, and we need to get to the point where we're sustaining rallies and scoring runs by driving guys in," he said. "When I look at a player's RBIs, the first thing I look at is I subtract the home runs. You subtract the home runs because they're knocking in themselves. That will really tell you how many runs they actually knocked in."
The homers by Castro and Krauss staked the Astros to a 4-2 lead in the sixth inning that they couldn't keep. The Royals rallied for a pair of runs in the seventh and then scored twice in the 11th to win, including a tiebreaking solo homer by Mike Moustakas off Jerome Williams.
"I hit it pretty good," Moustakas said. "I got underneath it a little bit. I hit it high. I didn't know how far it was going to go. I think it was a changeup. I was trying to stay on it, get something over to left-center field and it went out of the park."
The game marked the Major League debut of George Springer, one of the Astros' most anticipated prospects in years. He picked up an infield single in his second at-bat in the third inning for his first hit and scored on Castro's homer. He finished 1-for-5 with a run scored, a walk, a caught stealing and two strikeouts.
"I didn't necessarily hit it hard, and now I can go play from there and develop and have fun," Springer said.
His hit came in the third inning when he pounded a ball into the dirt and rolled a dribbler down the third-base line, beating out the throw. He grounded out in the ninth with a runner at first base and struck out in the 11th with a runner at first.
"We're glad he got it out of the way the first day," Porter said. "It's good to have him in the lineup. There's definitely some things that could happen when he's on the baseball field, the attention that he draws on the basepaths, it will give the hitters that are hitting behind him some pitches to hit as well, but it was good to see him get that first one out of the way."
The Royals scored twice against reliever Brad Peacock in the seventh inning to tie the game at 4. He allowed a pair of one-out singles, and Kevin Chapman walked a batter with two outs to load the bases. Salvador Perez singled up the middle on the first pitch from reliever Matt Albers to score a pair.
"That's a tough one to swallow there because we felt like we had the right guys that we wanted in each and every spot and we just didn't get it done," Porter said.
Astros starter Dallas Keuchel, who was battling a sinus infection, left the game with a 4-2 lead and a chance to win his second start in a row, but the bullpen couldn't hold the lead. Keuchel allowed two runs and six hits in six innings.
Keuchel, who held the Blue Jays to one run in seven innings last Wednesday in Toronto, walked one batter and struck out five while throwing 97 pitches in his third start. He gave up a solo homer to Danny Valencia in the second inning.
"You've got to go out there and battle," Keuchel said. "I was lucky enough to have good defensive plays the first couple of innings and kind of bailed me out until I got my feet planted a little bit in the fourth. I'll take it any day of the week. It's a good lineup over there and I'm just happy to get through six."
Castro sent an opposite-field homer to left off Royals starter Jeremy Guthrie in the third to put the Astros ahead, 2-1. The Astros took a 4-2 lead in the sixth inning when Jesus Guzman led off the inning with a walk and Krauss cranked a two-run homer to left-center. It was the first home run and RBIs for Krauss, who had a pair of hits. He entered the game with three hits in his previous three games after starting the season 0-for-15.
"It's good to square one up and drive it out," he said. "That's a good swing, something I can build on for sure. It's tough that's in a loss. You always wanted to help the team win, so I feel I failed today even though I had a couple of hits. I'd rather go 0-for and have a win than have a couple of hits and lose."