Triple-A All-Star in 2001. Following the 2001 minor league season, the Rangers called Peña up to the big leagues during September, when rosters expand. He made his big league debut on September 5, starting at first base, wearing number 15, and going hitless in three at-bats. Peña finished the 2001 season with a .258 batting average and three home runs in 22 games played. Oakland Athletics On January 14, 2002, along with Mike Venafro, Peña was traded to the Oakland Athletics by the Rangers for Jason Hart, Gerald Laird, Ryan Ludwick, and Mario Ramos. In 40 games with the A's, Peña hit .218 with seven home runs and 16 RBIs. During a stint with Triple-A Sacramento from July 2–5, he hit .438 with two home runs and six RBIs. Peña was mentioned several times in Michael Lewis' book Moneyball and was a minor character in the film based on the book. He is portrayed in the film by actor Adrian Bellani. Detroit Tigers Peña was involved in a three team deal on July 6, 2002. The Athletics sent Peña, a player to be named later (later named as Jeremy Bonderman), and Franklyn Germán to the Detroit Tigers. The New York Yankees sent Ted Lilly, John-Ford Griffin, and Jason Arnold to the Athletics. The Tigers sent Jeff Weaver to the Yankees and cash to the Athletics. The Tigers acquired Peña due to a season-ending injury to designated hitter Dmitri Young and the first baseman at the time of the trade for the Tigers, Randall Simon, immediately became the Tigers' designated hitter following Peña's acquisition. Peña made his Tigers' debut the next day against the Boston Red Sox, as he went 3–4 with 2 doubles and 2 RBIs. Peña played in 75 games for the Tigers in 2002 and batted .253 with 12 home runs and 36 RBIs. Overall, he batted .242 with 19 home runs and 52 RBIs in 115 games. His 2002 season included a 12-game hitting streak from September 8–21, which tied teammate Omar Infante for the longest hitting streak for an American League rookie in 2002. Peña played in his first full season in 2003 as the Tigers' everyday first baseman. On May 19, against the Cleveland Indians, he established career highs with 3 home runs and 7 RBIs. Peña also missed nearly a month in June when he suffered a left calf strain. He played in 131