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05/05/2013 4:30 PM ET

Richard heads to DL with intestinal virus

SAN DIEGO -- The Padres think they may have found a reason why pitcher Clayton Richard has struggled as badly as he has in his last three starts.

The Padres placed Richard on the 15-day disabled list prior to Sunday's game against the D-backs with what the team called an intestinal virus.

Richard, who is 0-3 with a 13.09 ERA in his last three starts, has struggled since initially his scheduled start on April 20 was pushed back because of a virus that caused him to sit out that day in San Francisco.

"It was really bad in San Francisco, then I started to feel better and then it went the other way again," Richard said after Sunday's game. "Now, it's being able to take a step back to get a better understanding of what's going on."

Richard said he had a similar experience five years ago when he was in the Minor Leagues with the White Sox, where he was sick and eventually had a relapse. But in that case, the virus simply went away.

"Initially, we thought it would be a few days," said Padres manager Bud Black, who said that Richard has lost 12 pounds in two weeks. "It's just hung on and he just can't shake it."

Richard, who will see a gastroenterologist on Monday, wasn't available for comment before Sunday's game. He allowed five earned runs in 3 2/3 innings in a loss to the D-backs on Saturday.

Black said Richard continues to exhibit symptoms that are typically associated with an intestinal virus. A handful of other players and some members of the coaching staff have a brief run-in with a virus, but it's nothing like what Richard has experienced, Black said.

"It's bounced around, but no one has shown it to the degree that Clayton has," Black said. "So let's run some tests, see a specialist and get a handle on this."

Richard, who is 0-4 with an 8.54 ERA in six starts, has been replaced on the active roster by another left-handed pitcher, Tyson Ross, who was reinstated from the disabled list. Ross landed on the DL on April 20 with a left shoulder subluxation.

Ross won't replace Richard in the rotation. The Padres, who have two off-days over a five-day stretch starting Thursday, will likely have Edinson Volquez start Friday's game against the Rays.

Ross comes off DL, but will begin in bullpen

SAN DIEGO -- Tyson Ross was reinstated from the disabled list just as Clayton Richard went on the 15-day DL with an intestinal virus.

Ross had been on the disabled list with a left shoulder subluxation, an injury he sustained on the follow-through to his swing when he got his first Major League hit last month against the Dodgers. He went on the DL on April 20, retroactive to April 18.

Ross made two relief appearances on a Minor League rehabilitation stint last week with Triple-A Tucson, allowing four runs on four hits with two walks and three strikeouts over 2 2/3 innings.

Before landing on the DL, Ross was 0-1 with a 3.86 ERA in three starts for the Padres. Now that he has returned, Ross won't take Richard's spot in the rotation. He'll pitch out of the bullpen for now, as the team still needs to be certain that he won't have a re-occurrence of the left shoulder injury again.

"They're just making sure I'm good to go," Ross said. "But I'm excited. It's been hard to sit out for two weeks. I think I'm right where I want to be."

Even if that's in the bullpen, and not the rotation.

"I would love to be in the rotation and swinging a bat," he said. "But I'm just going to focus on being a reliever at this point."

Baker confident in Cashner's potential as starter

SAN DIEGO -- Catcher John Baker has been behind the plate for each of Andrew Cashner's three starts since he joined the starting rotation last month.

Baker has liked what he's seen from Cashner, who will get the start Monday when the Padres face the Marlins in the first game of a three-game series at Petco Park.

"There's a ton of upside there," Baker said.

Cashner is 1-2 with a 4.50 ERA in his first three starts. He allowed four earned runs in four innings in his last start against the Cubs on May 1.

Cashner has displayed a live fastball in his first three starts and a good changeup at times, but for him to be successful moving forward, Baker said, he has to develop and trust another secondary pitch.

"It's finding a secondary pitch he can throw any time, especially when he's having trouble commanding his fastball," Baker said. "Once he does figure out what pitch that's going to be, it's developing the confidence to use it."

Two starts ago against the Giants, Cashner had a firm handle on his curveball, a pitch he used often in a victory when he allowed one run in six innings. But that curveball wasn't apparent in his last start against the Cubs when he struggled.

"In the bullpen, he can just throw his fastball by people," Baker said. "… But when you're throwing 100 pitches [as a starter], you can't do that."

Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.