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9/2/2013 5:21 P.M. ET

Flowers to undergo shoulder surgery on Thursday

NEW YORK -- Tyler Flowers' last at-bat of the 2013 season stands as a mammoth home run hit in the eighth inning off of Boston reliever Craig Breslow on Sunday.

This trying campaign for the first-year starter came to a premature end on Monday, when it was announced that the catcher will have exploratory surgery Thursday morning on a sore right shoulder that has bothered him for quite some time. Flowers is expected to miss three to six months, with fraying existing in his shoulder and the condition of the labrum dictating the length of absence.

The problem was discovered one year ago to the day Monday, according to Flowers. After consulting with White Sox head athletic trainer Herm Schneider, he has been doing the pitchers' shoulder program since.

"But there were a number of days in [Spring Training] where the pain was extreme," Flowers told a pool reporter by phone from Chicago. "It was a really tough [decision]. I've known I had to have surgery for a couple of months now. With the work I've put in to rehab, it was a good indicator. There was no way I could have continued with the pain level."

Flowers has seen three doctors over the past year, and had a recent MRI with contrast dye to pinpoint the issue.

"It solidified what I thought was going on," Flowers said. "As a ballplayer and an athlete, you know yourself better than everybody else. Initially when it happened, I thought it was more like a tweak. What got me was when I was getting ready for spring, it intensified, and that's when I started to question it.

"When [anti-inflammatories] wear off, you get the pain level and real feel. It was very extreme. It's something that has to be done. I could continue but couldn't perform at the level required by myself, my team or my teammates."

Getting the starting job with A.J. Pierzynski's departure via free agency was "definitely a driving force to exhaust every option I could," according to Flowers. Ultimately, Flowers finished the season with a .195 average, 10 homers and 24 RBIs, and will have to prove himself an everyday player once again next spring.

"You are looking at a guy that, defensively, he's been what you wanted and calls a great game," said manager Robin Ventura. "He does stuff around the plate that you like. Offensively, it's a down year. He's got to fight his way back offensively to be that guy. His potential is there to do it."

Santiago appreciates Cooper's tough love

NEW YORK -- Even before Don Cooper's Saturday rant on his distaste for walks and based upon Hector Santiago's wild Friday start, the White Sox left-hander knew his pitching coach was not pleased.

Santiago found out that fact firsthand when he came into the visitors' dugout at Fenway Park after throwing 101 pitches over just 3 2/3 innings.

"He was like, 'Are you trying to pitch around guys? Are you trying to pitch different? Why aren't you going after guys?'" Santiago told MLB.com on Monday of Cooper's weekend assessment.

"It was a little bit louder than the way I just said it," added Santiago with a laugh.

Pinpoint control has not been Santiago's forte this season, but he has been able to shake loose early struggles outside the strike zone in most starts to turn in a solid effort during his first season as part of the rotation. But Friday's self-described worst start of the year serves as a lesson in the growth process for a young pitcher and even a young catcher in Josh Phegley.

After getting squeezed on fastballs inside during the first inning Friday, by Santiago's estimation, he altered the game plan and stopped going inside. Santiago has the ability to throw six pitches, but throwing first-pitch breaking balls and sliders moved away from what Santiago wanted to do.

His goal is to simplify things when taking the mound for Thursday night's start in Baltimore, focusing in the early going on just fastballs and changeups. That's the blueprint he followed last September in Cleveland when Santiago one-hit the Indians over seven innings

As for Cooper's tough love, Santiago understands it's all geared toward improvement.

"You definitely appreciate him trying to get after you about what you are thinking right there in that situation," Santiago said. "When you are doing good, you want him to help you out just the same way.

"If you are out there and go six innings and have three walks, you still want to hear that tough feedback. He can give you both sides of the good and bad. It was definitely different. Coming in the dugout that day, it was a little blowup session. It was kind of aggressive, and I wasn't expecting it. It caught me off guard. It hasn't happened all year."

White Sox alter rotation for rest of road trip

NEW YORK -- The White Sox made slight adjustments to their starting rotation for the remainder of this 10-game road trip.

Wednesday's starter in New York officially is listed as TBA, as is Saturday's, when Andre Rienzo originally would have taken the mound in Baltimore. Hector Santiago moves from Wednesday's series finale against the Yankees to Thursday's series opener against the Orioles, with John Danks starting Friday and Jose Quintana on Sunday.

Erik Johnson, No. 2 on MLB.com's ranking of White Sox prospects, appears to be a prime candidate for Wednesday's start, with the right-hander expected to be called up from Triple-A Charlotte after the Knights' season ends on Monday. Johnson, who has a 12-3 record with a 1.96 ERA over 24 combined starts between Double-A Birmingham and Charlotte, last pitched Thursday.

Manager Robin Ventura mentioned Charlie Leesman as another starting candidate, but Leesman would seem an unlikely choice for Wednesday after throwing 82 pitches in relief on Sunday in Boston. Dylan Axelrod also is available.

Johnson, Semien to be among four Tuesday callups

NEW YORK -- When White Sox manager Robin Ventura was asked if he could provide the names of Tuesday's Minor League callups, he smiled and said that clubhouse manager Vince Fresso could do the honors.

The secret basically was revealed Monday morning, with clubhouse lockers set up for right-handed starter Erik Johnson, catcher Miguel Gonzalez, infielder Marcus Semien and right-handed reliever Daniel Webb. Semien, ranked No. 8 on MLB.com's White Sox Top 20 Prospects, figures to get a fair amount of chances at third base during the season's final month, but Johnson is the callup to watch closest.

He already has made a case to be part of the 2014 White Sox rotation and could further that argument over the next few weeks. The 23-year-old Johnson certainly has left a positive impression in the minds of his teammates.

"I would say he throws all of his pitches for strikes. He goes right after every hitter," said White Sox reliever Jake Petricka. "He throws everything in the zone. He just demands your respect when he's on the mound. He's dominant.

"Consistent, just in the zone, attacks all the time. Just a strong guy."

Third to first

• Reliever Ramon Troncoso has thrown two bullpen sessions and plans to throw live batting practice on Wednesday as he works his way back from inflammation around the lining of his heart known as pericarditis.

"We'll see how it goes," Troncoso said. "I have a light BP Wednesday, and we'll see after that how it feels. But right now everything is good."

"It's not like it was an arm injury or anything like that," Ventura said. "We are making sure everything is good with him, and if he is like that, I would pitch him again."

Avisail Garcia hit safely in 18 of the last 19 games. He left early in the one game missed after crashing into the right-field wall trying to catch Jeff Baker's homer on Aug. 25 against the Rangers.

Scott Merkin is a reporter for MLB.com. Read his blog, Merk's Works, and follow him on Twitter @scottmerkin. This story was not subject to the approval of Major League Baseball or its clubs.