Pena's slider is considered to have above average break, and his 4-seam fastball is better than his stats would indicate, judging by velocity and control.

He made his season debut on April 3 against the Colorado Rockies, tossing two scoreless innings of relief.

He pitched 12 scoreless innings of relief from June 5 to 28, the longest streak of the season by a D-backs reliever.

Peña picked up his first Major League hit on May 25 against the Houston Astros, a RBI single to right field.

On July 7, 2009, Peña was traded to the Chicago White Sox in exchange for minor leaguer Brandon Allen.

On August 31, 2014, Peña signed with the Chinatrust Brothers of the Chinese Professional Baseball League.

On July 1, 2015, Peña signed with the York Revolution of the Atlantic League of Professional Baseball.

He made 28 appearances (23 starts) for the team, compiling a 7-10 record and 5.58 ERA with 82 strikeouts across 138+2⁄3 innings of work.