ST. LOUIS -- The Cardinals' left-handed relief presence was down to one in a 6-4 loss to the Cubs on Monday after the club released J.C. Romero. That left Marc Rzepczynski as the lone lefty left in the 'pen.

The decision to part ways with Romero, who was signed to a one-year, $750,000 contract over the winter, was prompted both by his recent struggles and the team's need to get a fresh arm in a bullpen that just covered 14 innings in a three-game series. Right-hander Eduardo Sanchez took Romero's spot in the 'pen, and he threw a scoreless inning against Chicago.

"He's a lefty specialist that came in and was having trouble getting lefties at times," manager Mike Matheny said of Romero. "It got to a point where we felt we needed to do something."

After beginning the year with eight straight scoreless appearances, Romero struggled mightily in his last three. In a combined 3 1/3 innings, he allowed nine earned runs on 10 hits. The early success came predominately when he was used exclusively to get left-handed hitters out.

Romero, 35, has now been released in-season five times since 2007.

While clubs often prioritize keeping at least two left-handers in the bullpen, the need to meet a quota diminishes when a team has right-handed pitchers who are just as effective getting lefties out. The Cardinals believe that have two such pitchers in Victor Marte and Kyle McClellan.

Marte, who faced two lefties on Monday, has limited left-handed hitters to three hits in 21 at-bats this season. McClellan has held left-handed batters to a .179 batting average in 2012, well under the .210 career average they have against him.

"It's not just somebody that throws with the left hand," Matheny noted. "It's how they pitch to left-handed hitters."

Rzepczynski will continue to be used in late-inning, setup situations, both against right-handers and left-handers. Matheny also left open the possibility of calling upon him earlier in games if a particular matchup necessitates such a move.

Sporting better mechanics, Sanchez recalled

ST. LOUIS -- When the Cardinals sent Eduardo Sanchez out of big league Spring Training in mid-March, they did so with a directive to tighten up his mechanics and improve his command.

The improvements didn't come immediately, but they have been made of late, prompting the Cardinals to recall Sanchez from Triple-A Memphis after releasing J.C. Romero on Monday. Sanchez worked a perfect inning in the club's 6-4 loss to the Cubs at Busch Stadium later in the day.

"He pitched much better after those first few rocky starts," Cardinals farm director John Vuch said. "He simplified his mechanics a bit. He's definitely refined himself and has thrown much better here."

Those mechanical simplifications included shortening up his motion, which has helped Sanchez keep a more repeatable delivery. Recently, the adjustments led to an increased number of swings and misses.

In 14 games with Memphis, Sanchez allowed 10 runs (nine earned) on 12 hits and 10 walks in 13 1/3 innings. He struck out 13. However, he did not give up a run in his last five appearances.

"I'm a little bit surprised," Sanchez said, when asked about the callup. "I'm going to try to be here for all season long."

Sanchez was with the Cardinals for an extended period last year. He made 26 appearances in 2011, posting a 3-1 record and 1.80 ERA. He also saved five games.

Redbirds shuffle Minor League bullpens

ST. LOUIS -- The Cardinals' move to add Eduardo Sanchez into the big league bullpen created a ripple effect in the organization's Minor League system.

Taking Sanchez's spot in the Triple-A bullpen will be lefty Sam Freeman, who was a first-time participant in Major League Spring Training this year. He then began the season with Double-A Springfield, where he made 15 relief appearances before this promotion. In those 17 1/3 innings, Freeman allowed five runs (three earned) on 12 hits and four walks. He struck out 12.

"He's been pitching well down there," Cardinals farm director John Vuch said. "This is an opportunity to see him pitching at a higher level."

Though the Cardinals are down to one lefty in the bullpen, Memphis will now have four. Freeman will be joining Barret Browning, R.J. Swindle and Nick Greenwood. None of those three were considered ready to make the jump to the Majors as a potential replacement for J.C. Romero.

The organization also promoted right-hander Richard Castillo from Class A Palm Beach to Springfield, where he will move into the rotation. He'll take the spot that belonged to righty Michael Blazek. Blazek is headed to the bullpen after going 1-3 with a 6.61 ERA in seven starts.

"He's pitched good at times. He's pitched not so good at times," Vuch said of Blazek. "His best year being when he pitched out of the bullpen at [Class A] Quad Cities, so I think we saw him ultimately as a reliever. This was sort of the ideal time to do it."

Right-hander Todd McInnis will take the open rotation spot in Palm Beach.

The organization has also released outfielder Amaury Cazana, who was playing in Memphis. The Cardinals needed to open a spot there for Shane Robinson, who was optioned down from St. Louis on Sunday.

Worth noting

• Approximately 500 Tony La Russa-signed baseballs remain available from Nicko Sports, which recently began marketing 2,012 of the limited edition baseballs. They are available for $99, with $37 from each sale going to La Russa's Animal Rescue Foundation. The balls can be purchased online or by calling 1-800-345-2868

• The Giants have announced that they will start Madison Bumgarner (5-2, 3.80 ERA) and Matt Cain (2-2, 2.28 ERA) against the Cardinals when St. Louis travels to San Francisco for a two-game series beginning on Wednesday.