At 6 feet, 3 inches in height and nearly 300 pounds, the right-handed batting and throwing Peña is considered a pure power hitter best known for his long-distance home runs and high strikeout rate.

Pena debuted with the Reds as a September call-up in 2002, and got a single while pinch hitting in his first major league at-bat.

[1] Peña proved his label as a power hitter, hitting a home run in his second major league game, off Chicago Cubs pitcher Steve Smyth.

After platoon-mate Trot Nixon injured his biceps on July 30, Peña played more frequently in right field.

Peña hit a grand slam off closer Chris Ray of the Baltimore Orioles to help the Red Sox to a 5–2 victory on April 26.

[5] On April 20, 2009, Peña signed a minor league deal with the New York Mets and was assigned to Triple-A Buffalo.

[7] Peña signed a minor league contract with an invitation to spring training with the Arizona Diamondbacks prior to the 2011 season.

In a game against the Detroit Tigers on June 24, Pena launched a go-ahead homer an estimated 454 feet deep into the left-field seats at Comerica Park to give the Diamondbacks a 7–6 lead and the eventual victory.

In 76 minor league games that year, Pena hit 25 home runs with 77 RBI, with a line of .358 / .440 / .712 and an OPS 1.152.

[13] On November 29, 2011, Pena signed a 2-year contract with the Fukuoka SoftBank Hawks of the Nippon Professional Baseball (NPB).