During the 1995 MLB Draft, San Diego selected Allen in the 30th round. He made his professional debut that year, appearing in 29 games with the Idaho Falls Braves of the Pioneer League. He also saw action in 36 contests for the Class AClinton LumberKings of the Midwest League. For season, Allen posted a.292 batting average, 9 home runs, and 55 RBI. Allen appeared in 77 games with Clinton the following year, batting.267 and tallying 10 homers and 46 RBI. He also played in 55 games with the higher Class A Rancho Cucamonga Quakes of the California League, where he batted.298, with 10 homers and 45 runs batted in. Allen spent the entire 1997 season with the Class AAMobile BayBears of the Southern League. He batted.253 in 131 games, hitting 17 homers and driving in 75 runs. Allen split 1998 between Mobile and the Class AAALas Vegas Stars of the Pacific Coast League. He batted.253, with 6 homers and 42 RBI in 42 games with Mobile. With Las Vegas, he saw action in 87 games, recording a.267 average, 16 homers, and 45 runs batted in. He returned to Las Vegas for the 1999 season, appearing in 128 games. He batted.273, hit 18 home runs, and drove in 89 runs. In 2000, Allen batted.311 in 67 games with Las Vegas, tallying 14 homers and 55 RBI. He joined the Padres during the season and made his MLB debut on July 1. Pinch-hitting against Colorado Rockies pitcher Mike Myers in his first at-bat, Allen lined into a double play. Allen appeared in 9 games for the Padres, going hit-less in 12 at-bats.
Detroit Tigers (2000–2001)
On July 17, 2000, the Detroit Tigers acquired Allen from San Diego in exchange for Gabe Alvarez. Allen batted.222 in 25 games for Detroit's Class AAA affiliate, the Toledo Mud Hens. His offensive performance improved significantly after he was promoted to Detroit, as he batted.438 in 18 games with the Tigers. On August 14, Allen recorded his first MLB hit, a double, off Seattle Mariners pitcher Joel Piñeiro. His first MLB home run came on August 29, when he hit a solo homer off Baltimore Orioles pitcher Chuck McElroy. On October 1, Allen homered off Minnesota Twins pitcher Eddie Guardado in what would prove to be his final MLB at-bat. In 2001, Allen's final professional season, he saw action in 29 games for Toledo. He posted a.218 batting average, 4 home runs, and 11 runs batted in.
Personal life
Allen graduated from Stanford University in 1995, having earned bachelor's degrees in psychology and economics. He is currently the President and CEO of Westgate Business Services.