Against the Tigers Wednesday, Pena went 2-for-5 with two runs and a strikeout.
"He swung the bat a little better [Wednesday]. He's going to swing and miss but he does have the potential to hit the ball out of the ball park," Rangers manager Ron Washington said. "He got him two [hits] tonight, and that's a good start for him. He's going to be OK. He will be OK."
Pena was selected 10th overall in the first round of the 1998 June First-Year Player Draft. His last home run in Arlington was in Game 3 of the American League Division Series in 2010.
The challenge in hitting, he said, is in controlling emotions.
"Pitchers will use that aggressiveness against you," he said. "It's so important to stay calm and be able to manage emotions and keep them under control."
Though the 36-year-old said his home run would've been sweeter had the Rangers pulled out the victory, Pena said he's thrilled to just be competing in the big leagues again.
"I'm going to tell you something," Pena said. "It's only by the grace of God that I'm here. And I cherish every single moment."
Grace Raynor is an associate reporter for MLB.com
This story was not subject to the approval of Major League Baseball or its clubs.