Versatility and speed are his biggest strengths, as Harris has the ability to play all three outfield positions as well as second base, where he started 28 games in 2005.

He went to spring training camp as a non-roster invitee, but he was figured to have a strong chance to make the Opening Day roster.

On June 30, Harris tied a career personal record with 3 stolen bases in a 6–5 win over the Miami Marlins.

He posted a remarkable night on July 21: In a 14–6 rout of the St. Louis Cardinals, Harris went 6-for-6 with four singles, two triples, six RBI, four runs scored, and a stolen base.

On August 9, the Braves were beating the NL East-leading New York Mets 7-3 entering the bottom of the 9th at Shea Stadium.

After Braves reliever Tyler Yates yielded three runs to bring the Mets within one, Óscar Villarreal came on to pitch.

The first hitter he faced, first baseman Carlos Delgado, hit what appeared to be a solo home run to make it a tie game.

Harris ranged back in left field, stopped just before the wall and jumped, robbing the home run and preserving the lead.

On August 22, 2008, Harris hit his 11th and 12th home runs of the year, including his first career grand slam that gave the Nationals a 6–4 lead.

He also hit a two–run home run, collected 6 RBI to give him 38 for the season, scored 3 times, and stole a base in the Nationals' 13–5 win against the Chicago Cubs at Wrigley Field.

According to reporter Anthony DiComo, Harris "is all but a lock to make the team in an arrangement that should net him between 250 and 400 plate appearances" in 2011.

Harris was named as the Manager of the Richmond Flying Squirrels in the San Francisco Giants organization for the 2018 season.