ST. LOUIS – After setting themselves up for a chance at a momentum-building sweep of a foe for a sixth time this season with some stellar play over the previous two days, the Cardinals experienced a similar unfulfilling feeling on yet another forgettable Sunday at Busch Stadium.

And in some ways, the Cardinals had only themselves to blame for the sloppy 11-3 loss to the Red Sox before 39,316 fans. On Sunday, the Cards not only rested the bats of red-hot rookies Masyn Winn and Iván Herrera, but they also started converted reliever Matthew Liberatore for a third time in place of injured starter Steven Matz, who has been on the injured list since May 3 with a low back strain.

The left-handed Liberatore, who thrived earlier this season as a short-burst reliever, came into the day holding lefty hitters to a .161 average, but righties had touched him up for a .314 average and a .929 OPS.

Sunday’s script held form in Liberatore’s three-plus innings, in which he surrendered six hits and four earned runs to the previously slumping Red Sox: While lefties were 0-for-4 with two strikeouts, right-handed hitters were 6-for-11 with a home run from former Cardinal Tyler O’Neill and run-scoring doubles by Garrett Cooper and Romy Gonzalez.

The Cardinals’ defeat dropped them to 2-13 in series finales, 1-7 on Sunday and 0-6 in series finales in which they had a chance to sweep. The Cards went up 2-0 on the Padres, Marlins, A’s, Mets, Angels and the Red Sox in series earlier this season, but they dropped the finale each time.

“It would be cool to sweep some teams, but at the end of the day, it’s about winning the first game of the series, clinch the next day and then go for the sweep on the third day,” said left fielder Brendan Donovan, who had a single and an RBI on Sunday. “At the end of the day, we’re winning series and we’re starting to swing the bats. We’re trying to find some positives and silver linings in how we’re playing.”

Of course, the Redbirds can hardly afford such series slipups considering that they have spent exactly one day above .500 this season (they were 5-4 on April 6) and they came into Sunday trailing the Brewers by seven games in the NL Central. Then, there’s this: They are just 1-6 against those Brewers, a team they beat a week ago to avoid being swept.

“Momentum is huge, and sweeps do that for you, but I think everybody in this clubhouse knows where we’re at, and we’re moving in the right direction,” Liberatore said of a Cards club that has won five of its last seven games. “We’ll flush this and come back tomorrow ready to win a ballgame.”

The Cardinals have now lost two of Liberatore's three starts. In 10-plus innings, he has an 8.10 ERA while giving up 14 hits. His inability to perfect a cutter has hurt his chances of consistently getting out right-handed batters, and his deviating velocity as a starter certainly hasn’t helped.

The Cards stuck with Liberatore for three starts instead of turning to one of their Triple-A starters, with manager Oliver Marmol repeatedly insisting, “he gives us the best chance to win.” Marmol said the club will have to reevaluate their plan going forward before that slot in the rotation rolls around again.

“It’s tough, because he’s taken his best shot, so it’s nothing against his preparation or execution, but he’s taken his best shot for the situation we’re in,” Marmol said of Liberatore. “We do [need to reevaluate the plan] -- out of fairness to [Liberatore], as well. This is a guy who was settling into a bullpen role and doing his job and now he’s filling a need for us.”

Left-hander Zack Thompson beat out Liberatore for the No. 5 starter job in Spring Training, but he was sent back to Triple-A Memphis following a rough Major Leauge start highlighted by his lack of velocity and unexpected weight loss in the offseason. In four games and three starts with Memphis, Thompson has gone 1-0 with a 1.84 ERA while allowing foes to hit just .125 off him.

Sem Robberse (5-2, 3.29 ERA), Andre Pallante (1-0, 2.20 ERA), Gordon Graceffo (4-3, 4.32 ERA) and Michael McGreevy (2-4, 5.84 ERA) are other Triple-A options who the Cardinals could consider when the No. 5 spot in their order rolls around in the weekend ahead.

“We have to look at that and see what’s best all the way around,” said Marmol, who noted how moving Liberatore to the starting rotation also weakened the Cardinals bullpen.