He began the 2010 season with the AAA Oklahoma City RedHawks, but was called up to the majors on April 27 due to Nelson Cruz being placed on the 15-day disabled list.

In 2013, Gentry hit two home runs, stole 24 bases and had an on-base percentage of .373, all career highs.

[9] Gentry was named Rangers' player of the month in September after batting .354 with 10 stolen bases, 10 runs, 2 doubles, a triple and four RBI.

[14] On December 3, 2013, Gentry, along with pitcher Josh Lindblom, was traded to the Oakland Athletics for outfielder Michael Choice and infielder Chris Bostick.

[15] Gentry missed much of spring training in 2014, due to a lower back strain he suffered on the first day of workouts.

[18] On July 27, he suffered a broken right hand when hit by a pitch during a bunt attempt against the Texas Rangers.

[19] On September 9, Gentry suffered a season-ending concussion after a collision at first base with Carlos Sanchez of the Chicago White Sox.

[26] On April 16, Gentry hit his first home run with the Orioles, a two-run blast off Matt Dermody.

Gentry hit a walk-off single on July 31 against Joakim Soria of the Kansas City Royals.

On February 14, 2019, Gentry signed a minor league contract with the San Francisco Giants.