CHICAGO -- A bullpen that has been stalwart all month was exposed just enough on Sunday, leaving the Cardinals to swallow yet another tight loss -- this one by a 4-2 final in front of 39,534 at Wrigley Field.
The outcome meant the Cardinals also had to shoulder a series loss to the Cubs after riding a string of seven wins in eight games heading into the weekend. Chicago, though 14-9 this month, is an unthreatening 42-58 on the season.
"We can't be playing well and come in here and lose to the Cubs," outfielder Matt Holliday said. "We can't lose this series. But we did. The only way to get better is to play better. We didn't get the result we were looking for."
Don't look now, either, as the Cardinals have fallen 7 1/2 games behind the National League Central-leading Reds, who have reeled off 10 consecutive victories. The Cardinals haven't stared at a division deficit that daunting since 2011, when they had to earn a Wild Card berth in order to play in October.
"We need to focus on winning ourselves," said Carlos Beltran, who snapped an 0-for-13 skid with a game-tying homer in the eighth. "We have no control of what Cincinnati is going to do, or [second-place] Pittsburgh. We have to find a way to focus on playing the game and win ballgames. We have plenty of games left, and anything could happen."
For all the good there has been this month -- consistently good starting pitching, a mostly dominant bullpen, outbursts by the offense -- the record isn't all that indicative of it all. Rather, close losses continue to be a culprit. The Cardinals are 16-29 in games determined by two or fewer runs.
A 2-2 game advanced into the 10th, with the Cardinals' bullpen riding a scoreless-innings streak of 19 2/3 frames. With manager Mike Matheny holding closer Jason Motte until his team took a lead, two options remained -- rookie Trevor Rosenthal or lefty Brian Fuentes, who had pitched on consecutive days. Rosenthal hadn't pitched since July 23.
Matheny turned to Rosenthal, who would have been able to offer multiple innings of work had the Cubs not ended his day after six pitches.
Starlin Castro's leadoff single was followed by Anthony Rizzo's blast into the left-field bleachers.
"I'm just trying to be aggressive there and maybe I was being a little too aggressive on that pitch to that hitter," said Rosenthal after his fourth Major League appearance. "I thought we had the right pitch and the right location -- it just caught a little bit too much of the plate."
"He came in and threw strikes," Matheny added. "A young pitcher coming into this environment and throwing strikes right from the top, that's what you want. It just didn't work out."
The walk-off homer was Rizzo's first at any level. As for the Cubs, four of their last six home wins over the Cardinals have come with a walk-off knock.
"I'm not really trying to move him over there," Rizzo said. "I'm trying to do some damage. My approach is [to] just be as simple as possible."
The outcome overshadowed an afternoon where again the Cardinals received sufficient starting pitching. Adam Wainwright allowed a run in each of the first two innings but quickly adjusted his game plan when he realized he would not be able to rely on his fastball or changeup.
Instead leaning heavily on his curveball and cutter, Wainwright wrapped up his six-inning start by facing the minimum in each inning after the second. A pair of double plays helped his cause, though another not turned back in the second had already helped a run score.
"The outcome was good, but the process of getting there was kind of battling," Wainwright said. "My fastball command was terrible early. It got a little better, but it wasn't great by any stretch of the imagination."
Though disappointed with his fastball command in each of his last two starts, Wainwright has pitched well enough that seven of his last nine outings have been quality starts. He wraps up July with a 2.75 ERA and now sits with a season-low mark of 4.24.
The Cardinals' offense had few chances early against Cubs starter Paul Maholm, whose line included only two hits and two walks through six innings. But perhaps extended too far, Maholm became vulnerable in the seventh.
David Freese extended his hitting streak to a career-long 10 games with a one-out single. He moved to third on a double by Matt Carpenter. Tyler Greene's sacrifice fly scored one, and Maholm's day ended when he then walked consecutive batters to load the bases.
Allen Craig flied out against reliever Manuel Corpas to silence the threat. That made Maholm the first Cubs left-hander in modern history to make six consecutive starts of at least six innings with no more than one run allowed.
"That's the best lineup in the National League, and by far the best right-handed-hitting lineup, too," Cubs manager Dale Sveum said. "And he did a heck of a job against the best."
Beltran's 23rd homer tied the game in the eighth. The potential tying run was left at second in that inning, which was the last time the Cardinals advanced someone that far.
In the series, St. Louis went 1-for-15 with runners in scoring position. Since the All-Star break, the club is 9-for-66 in such spots on the road.
"I think we've left something on the table in every period that we've played so far," Wainwright said. "But you're talking about a team that knows how to win and knows how to get it done. Things will click soon. I really feel that. We're really taking it serious, really trying hard to make the adjustments."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.