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6/15/2014 2:47 P.M. ET

Starters keeping hits on ground during turnaround

MIAMI -- A lot of the Pirates' success in June has been credited to the offense, which entered Sunday leading the Majors in batting (.300) and runs scored (72) for the month -- but the team's starting pitching had provided just as much of a push in Pittsburgh's journey back to .500.

The Pirates starting staff entered Sunday with a 2.72 ERA in June, the second-best in baseball, after registering a Majors-worst 4.92 ERA in May.

Manager Clint Hurdle credited the turnaround to an increased rate in ground balls, which allowed starters to give up fewer extra-base hits. Entering Sunday, the rotation had allowed 18 extra-base hits in June, compared with 111 across the first two months of the season.

"Things are getting better individually and collectively as the group has moved forward," Hurdle said. "Our ball on the ground rate has spiked dramatically in the last 30 days. Retiring hitters on three pitches or less has gotten better. ...Now our numbers are starting to get back to where we believe we can keep them."

Cole throws bullpen, with sim game to follow

MIAMI -- Gerrit Cole threw 35 pitches in a bullpen session on Sunday. Though he had some issues with the execution of his pitches, he noticed progress.

"A little rusty on the timing, ball was up, but it was defined," Cole said. "So it was good. It felt like a normal, midweek 'pen."

If Cole feels well Monday, he could still pitch a simulated game during the home series against Cincinnati. The date is flexible because of Monday's off-day, but manager Clint Hurdle projected it for Wednesday.

The status of Francisco Liriano, who landed on the disabled list with a left oblique strain, is less defined. Hurdle said Liriano had been doing cardio and may start throwing on Thursday.

"We're going to be very open-minded with his return because, number one, we gotta get him to the point where he can throw the ball without any discomfort," Hurdle said. "I think it's actually good for him right now to unplug mentally. I wouldn't say he's behind [schedule] but definitely not ahead."

Neil Walker, recovering from an appendectomy, has been running drills at Marlins Park and could start swinging the bat on Tuesday.

Worth noting

• To activate Sunday starter Vance Worley, the Pirates optioned infielder Michael Martinez to Triple-A Indianapolis before the series finale at Marlins Park. Martinez's contract was selected on Thursday, and he went 0-for-3 with a walk in Friday's 13-inning victory in Miami.

• The Pirates have sent left-hander Blake Taylor to the New York Mets to complete the trade from April 18 in which the Pirates acquired Ike Davis.

Taylor was Pittsburgh's second-round selection in the 2013 First-Year Player Draft.

Maria Torres is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.