D-backs to keep a close eye on Corbin down the stretch

PHOENIX — After talking with general manager Kevin Towers on Tuesday, manager Kirk Gibson said the Diamondbacks will monitor Patrick Corbin’s next start Friday in San Francisco with an eye toward his long-term health.
Shutting Corbin down was not mentioned, but it would appear to be a possibility if his inningscontinue to rise and the D-backs continue to fall the in the race for the second NL wild-card spot. 
In other business, Gibson also said that while he believes right fielder Gerardo Parra is a dominating defender, he needs to make an adjustment against left-hander pitchers or possibly fall into platoon-player status.
First to Corbin, who is scheduled to face Yusmeiro Petit at AT&T Park. Corbin gave up five runs in five innings when the two met Sunday, and he has given up 13 earned runs in 10 1/3 innings in his last two starts.
“We will have some special interest to see how Patrick throws. If he struggles again, then we may get him more rest, whether it is inserting a sixth guy (into the rotation), or there are a couple of other ideas,” Gibson said.
“For sure, that is the one guy … we don’t want to push him. He has a lot of innings right now. A guy we want to make sure we don’t hurt him.”
Corbin, 13-5 with a 2.96 ERA, has been the D-backs’ best pitcher, and he was one of their two All-Stars in his first full season in the majors. But the D-backs will be prudent, especially after seeing young New York Mets’ right-hander Matt Harvey go down with a season-ending elbow injury two weeks ago. 
Corbin has pitched 182 ⅔ this season, 3 ⅔ fewer than he pitched at three stops last season season, when he spent the final two months in the D-backs’ starting rotation. He pitched the full six months in 2012, but some of those innings were as a reliever and not as many were as stressful as they have been this season. He would have five more starts if he stayed in turn the rest of the way. 
Against the Giants, the D-backs did not see the same bite on Corbin’s slider, the pitch Todd Helton in May called the best slider he has ever seen. They also noticed that he had a hard time getting the ball to the inside part of the plate against right-handed hitters, another staple of his attack this season. Hunter Pence hit an outside fastball down the right-field line for a homer Sunday, a pitch that was supposed to be inside. 
“In the really good games that he’s pitched, he’s struck everybody out on the sliders on the (pitcher’s) glove side, and they are breaking sharply down and in. Just didn’t get it there,” Gibson said.
“His velocity is maybe down a tick. The game before his velocity was down right out of the gate. It just didn’t feel like he had good rhythm. He usually is always able to get that strike right on the inside corner. He may have got one of those last game. That has a big impact, influences the hitter on how successful his other pitches are.”
Corbin said several times after the game that he felt fine, but the D-backs know what they saw. 
David Holmberg is scheduled to start Class AA Mobile’s second game in the Southern League playoffs, and he would not be an immediate option.
Parra, 26, already has 60 more at-bats than he has had in any of his previous four seasons here. He has set career highs with 33 doubles and 10 home runs, and his defensive WAR rating is the best among NL right fielders. For all that, Parra has yet to find an answer against left-handed pitchers this season. A .256 career hitter with six homers 43 RBIs against leftties entering the season, he is hitting .208 with no homers and three RBIs in 154 at-bats against them in 2013.
“He’s gone all out for us,” Gibson said.  “He’s grown as a player. He’s dominating defensively, yet he’s got a long way to go. He could make some adjustments and become a much better player. That’s everybody.”

Against left-handers, Gibson said, “just the arm angle, something he doesn’t pick  up. You see the feet get a little quicker on him. That’s an area he needs to get better at, or we need to put him more in a platoon-type situation.”