"Depending on how the surgery goes, it may cost him the rest of the season," Phillies general manager Matt Klentak said.
Valentin is the organization's No. 29 prospect, according to MLBPipeline.com. He hit just .229 with a .573 OPS through 29 games with Lehigh Valley. Double-A Reading second baseman Scott Kingery is the Phillies' No. 11 prospect. He is hitting .289 with 13 home runs, 27 RBIs and a 1.018 OPS through 37 games, but he is expected to remain in Reading for the time being.
"Very possible down the road," Klentak said about Kingery's promotion. "We've got more than enough infield coverage [at Lehigh Valley] to be fine and Kingery is good where he is."
Kendrick is getting close. Phillies left fielder Howie Kendrick has been on the 10-day disabled list since April 16 because of a strained right abdomen. He could begin a rehab assignment sometime this week.
"We have to be cautious about that just because you don't want to go too far and too fast," Klentak said. "You look at a day like today where things are wet and cold and everything is slippery. It's not the best day to run around. We're subject to Mother Nature as well. We'll see."
Herrera is fine. Odubel Herrera took heat for not running to first base on a ball hit in front of the plate in the ninth inning Sunday in a 1-0 loss to the Pirates. Phillies manager Pete Mackanin said he had no issue with the play because Herrera did not see the ball.
"When you hit a ball like that in the batter's box and you can't even see the ball -- I don't blame him for not running. It's like a surprise," Mackanin said.
Mackanin spoke to Herrera a little more than a week ago about his focus and play. He said Herrera has improved in that regard, despite his continued struggles at the plate.
"Since that talk he's been doing what he should be doing," Mackanin said. "If they don't run it's not because they're lazy. If you watch Herrera in the outfield he works his [rear end] off. I feel he's been better."
Todd Zolecki has covered the Phillies since 2003, and for MLB.com since 2009. Follow him on Twitter and Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.