Determined to change that, Parra made some adjustments in his stance, keeping his hands closer to his body and relaxing his front leg more. The idea was to get him to use his hands more and stay back, rather than fly open.
It's obviously too soon to say if the changes are a success or not, but Monday's home opener was a good start, as Parra singled and drove in two runs against Giants lefty Madison Bumgarner, putting him halfway to his total from last year.
"I feel more comfortable against them," Parra said. "I don't put too much pressure on myself against them now."
D-backs manager Kirk Gibson played Parra against lefties more often during Spring Training and also put him in simulated games against them.
"He changed his whole setup," Gibson said. "His setup is different, his hands are different, he's trying to put himself in better position."
So far, so good.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.