"Definitely in a rhythm right now," Norris said. "I've been working really well with Castro. Things have been there for me. I just want to keep it going."
Norris, who entered with a Majors-best 0.54 ERA this month, saw his monthly mark drop to 0.35 and his cumulative ERA to 3.14. He certainly had to work for the victory as the Cubs put runners in scoring position in each of the first five innings.
Each time, though, Norris was able to record the final out of the inning without any damage, whether by groundout, flyout or strikeout. The Cubs left 10 men on base.
"I made some good pitches in scenarios and luckily enough, I've been getting outs," Norris said.
Cubs manager Dale Sveum stacked his lineup with six left-handed hitters in an effort to take Norris' powerful slider out of the equation. But Norris was able to use his slider, sinker and changeup effectively, allowing five hits in seven innings.
Norris knows that players look at his numbers against left-handed batters and see an opportunity to get some hits.
"I've been learning," Norris said. "That's something across my career that I've had to get better at, is getting left-handers out."
The Astros did their part, getting to powerful Cubs starter Matt Garza (2-2) early. Castro's second-inning homer, a shot to right field on an 0-2 pitch, came after a two-out single by Johnson and a walk by J.D. Martinez.
"That's the name of the game right there," Johnson said. "Just keep the line moving. Doesn't really matter how many outs you got. Just keep grinding. Keep getting different guys up to the plate."
Castro said getting a homer in that situation will boost his confidence at the plate. He entered Monday's game with a .209 batting average.
"It was a tough at-bat," Castro said. "I got behind and I had a pretty good feeling he was going to come in with something, so I got a slider out a little bit and I was able to put a pretty good swing on it."
It was Castro's first home run in 227 at-bats. He last went deep at Wrigley Field on July 19, 2010.
"It's been too long, so hopefully we can break that trend," Castro said.
After a two-out RBI single from first baseman Carlos Lee in the third inning, the Astros led 4-0. Brian Bogusevic walked before Johnson launched a 2-1 Garza offering an estimated 429 feet over the wall in right-center field.
"The thing with [Johnson] is he was very disciplined staying off some breaking balls and then he was able to catch up to a fastball and hit it a long way," Astros manager Brad Mills said.
Garza departed after the third inning having given up seven earned runs.
"I was overthrowing everything," Garza said. "I put myself in holes and when you put yourself in holes, you can't make a mistake and you have to be perfect, and not even perfect, but you can't leave it out over the plate."
In the seventh inning, Jed Lowrie hit the Astros' third home run, his seventh of the season and his third in the last five games. Lowrie has the most home runs of any National League shortstop.
Enerio Del Rosario, just called up from Triple-A Oklahoma City, and Fernando Abad gave up four runs in the ninth to make the final score a bit closer.
Johnson said he and his teammates are starting to get the feeling that Norris will be this good every start.
"It's kind of comforting knowing that Bud's on the mound because we know if we get a couple runs, Bud's probably going to make that stick," Johnson said. "That's the nice thing about having a guy like that on the mound."
Castro also praised Norris.
"He's doing a great job of not making big mistakes," Castro said. "He's missing where he needs to miss and he's being smart with his pitches. It's not like he's keeping guys off the base every inning. He's getting some guys on there and he's battling out of situations, and that's a testament to him.
Mills said he wouldn't argue with the idea that he's never seen Norris better.
"I think he's putting himself in a situation to win ballgames and for the ballclub to win these games," Mills said. "That's huge."