CHICAGO – The same-old performance and offensive struggles are starting to wear on manager Dale Sveum as the Cubs sit 22 games under .500.

In a sloppy performance in front of a national TV audience – the Cubs and Red Sox combined for four errors and numerous mishandles in the field – yet another lefty starting pitcher handcuffed the North Siders’ offense in a 7-4 loss in Sunday night’s series finale at Wrigley Field.

The Cubs displayed no patience at the plate against Boston’s Franklin Morales, who started his first game since 2009 with Colorado, failing to draw a walk. Morales struck out a career-high nine batters and owned the Cubs’ Nos. 5-9 hitters, who went a combined 0 for 10 with eight strikeouts.

The Cubs are the only team in the majors with fewer than four wins against left-handers, dropping to 3-15 this season.

“It’s the same story,” Sveum said. “Left-handed pitcher, we were getting beat constantly on a fastball. That’s the bottom line. It wasn’t like he was doing a whole lot else besides throwing a lot of fastballs.

“You can’t even try and do what we do against left-handed pitching,” Sveum added. “It’s very difficult to have those kind of numbers and slugging percentage and everything like that against left-handed pitching on a consistent basis.”

Starter Paul Maholm did his best to keep the Cubs in the game. Although Maholm earned a no decision in Sunday’s outing, he recorded his second straight quality start. Boston (33-33) managed three runs on six hits against Maholm in the lefty’s six innings. Maholm walked only one batter while striking out six, one shy of his season high.

“Every guy in the locker room is busting it,” Maholm said. “They’re prepared; they’re doing everything they can. We’re just not coming up with the hit, not coming up with the big pitch. It’s on us. We’ve got to go out there and do it.”

Maholm was headed for disaster after the Red Sox struck for two quick runs in the first inning. Boston grabbed a 1-0 lead two batters into the game on Dustin Pedroia’s RBI double and scoring on David Ortiz’s one-out single. He settled down, though, retiring seven of the next batters, which included striking out the side in the second. Ortiz’s fourth-inning solo homer was Boston’s only other run off Maholm.

A Cubs error in the seventh helped Boston score three runs to break the 3-3 tie, the last run scoring on a perfectly executed suicide squeeze play.

“In the first, I think they put together a couple good at-bats, obviously, put the ball in play,” Maholm said. “They’re a good lineup from top to bottom. You got to make an adjustment. You got to execute your pitches from there on out.”

Terrible Red Sox defense allowed the Cubs (22-44) to erase a one-run deficit in the sixth. Jeff Baker appeared to ground into an inning-ending double play on a ball hit back to Boston pitcher Matt Albers. But second baseman Pedroia and shortstop Mike Aviles both went to cover second base and the confusion allowed the ball to drop, scoring Darwin Barney from third to tie the score, 3-3.

However, the Cubs could not capitalize with runners on first and second and one out as Joe Mather and Welington Castillo grounded out to end the sixth. They left seven runners on base in the loss.

Starlin Castro, stuck in a 2-for-21 slump, got the Cubs a run back in the first on his RBI triple. He added a game-tying two-out RBI double in the third on Pedroia’s dropped pop up in shallow right field that drove in Darwin Barney, who hustled and scored from first. Castro went 3 for 4, finishing a home run shy of hitting for the cycle.