The Cubs out-hit the Brewers, 4-3, but Chicago pitchers also combined to walk six and hit three batters.
"When you walk more than the other team, you're going to lose 70 percent of the time," Sveum said. "You've got to throw strikes to pitch in the big leagues. We have to do a better job of that."
Rusin (0-1) tried to help himself when he tripled in his first big league at-bat, lining the ball to right-center with one out in the third, but was stranded. According to Elias Sports Bureau, no Cubs pitcher has ever tripled in his first Major League at-bat. Bob Muncrief did triple in his Cubs debut on June 8, 1948, but that hit came in his second at-bat. The last Cubs player to triple in his first career at-bat was Dan Rohn on Sept. 2, 1983, in his second plate appearance.
"I just closed my eyes and swung," Rusin said. "I didn't know where it was going. It happened to go over the outfielder's head."
It was his first extra-base hit, period. He did not have one in the Minor Leagues.
"It was pretty exciting," Rusin said.
"I don't know how many times the first pitch a pitcher has ever seen he hits a triple -- maybe a home run, but I don't know about a triple," Sveum said. "We knew he could swing the bat. He lined out another time, too. He did all right."
Good enough to warrant another start? Sveum, who was impressed with Rusin's changeup and his ability to recover when he fell behind, said they'll consider their options.
"It's whatever they think," Rusin said. "If they decide to keep me here, I'll do my best. If not, I'll do the same thing down in Iowa."
The Brewers want to see Rusin again.
"That first guy really kind of mystified us a little bit," Milwaukee's Jonathan Lucroy said. "I guess when you've got a really good changeup like that, you're able to keep a lot of guys off balance. He would drop a changeup on you that was painted, a borderline [strike], and would get you to roll it over. ... That guy did a nice job for his debut, and I'm sure we'll be facing him down the road again. I can't wait."
He certainly would boost attendance. Rusin had a large crowd of family and friends in the crowd of 29,179 at Miller Park, including his parents, who made the seven-hour drive from Michigan.
The young left-hander showed he can field his position, handling a comebacker by Estrada and throwing the pitcher out to end the third.
But his foot got in the way in the fourth. The Brewers loaded the bases with one out as Rusin hit two batters and walked another. The first hit off Rusin was literally off the pitcher, as Corey Hart lined an infield single off his left foot. A run scored.
"It hit the top of my foot," Rusin said. "It stung a little bit, but I'll be fine."
Sveum decided to pull Rusin after 70 pitches.
"He did a good job, came out of there with his head up," Sveum said.
Rookie Alberto Cabrera walked the bases loaded in the sixth and a run scored on a wild pitch. Lucroy followed with a two-run double to open a 4-0 lead and preserve the win for Estrada (1-5), who struck out nine over six innings.
"Estrada is a nice pitcher, but I wouldn't expect him to have nine strikeouts in six innings, either," Sveum said. "We didn't do a real good job of taking advantage of what I thought were a lot of good pitches to hit and a lot of went down lookings on some pretty good pitches to hit. That was unfortunate."
For the second straight day, the Brewers struck out 12 Cubs. They've helped Milwaukee pad its K's totals, which is already tops in the National League at 1,042.
The Cubs scored two runs in the ninth against Manny Parra, including an RBI single from Alfonso Soriano.
Rusin is the 16th rookie to play for the Cubs this year, and 10th to make his Major League debut. Of the 16, he's the ninth pitcher. The last time the Cubs had more than 10 players make their big league debut in the same season was 2010, when 11 did so.
Rusin admitted to being a little nervous, but was able to retire the side in an efficient first. Whether he'll be part of the Cubs' rotation next season is still to be determined. He, Brooks Raley and Justin Germano are among the candidates for spots.
"They're young guys who are still learning how to get Major League hitters out with the stuff they have," Sveum said. "That's what the evaluation point of all this is. That's what we have, that's the depth we have and we're going to evaluate it going forward. They have the ability to do it. Now, it's the understanding how to do it on a daily basis against Major League hitters."
"It's always a good opportunity to get out there and do as good as you can and take advantage of it," Rusin said. "I thought I did all right, but we didn't get the win."