In 2004, the Pirates named him their minor-league player of the year after he hit .301 with 38 home runs and 137 RBIs for the Single-A Lynchburg Hillcats and the Double-A Altoona Curve.

He was promoted to the Pirates' major league roster on July 21, 2005, after he hit .297 with 28 home runs and 75 RBIs for the Curve and the Indianapolis Indians.

[citation needed] Eldred got injured in the first week of the 2006 season, and was unable to play for the rest of the year.

After a strong Spring Training in 2007, in which he began playing the outfield to increase his versatility, he was added to the Pirates' opening day roster.

For the AAA Charlotte Knights, he hit 38 home runs and 100 RBIs, leading the International League in both categories.

On January 14, 2011, Eldred signed a minor league contract with the San Francisco Giants with an invite to spring training.

In 2016, he was limited to 95 games due to injury, but still batted .294 with 21 home runs, helping his team to a playoff spot.