For example, when Elijah Dukes went down with a right hamstring strain last Friday against the Indians, Harris was put in center field and showed he has good enough range to catch balls in the gaps.
With Ryan Zimmerman out with a tight right hip flexor the past few games, Harris started at third base and has been more than adequate at the position.
While he is not hitting for average, Harris has shown he can work the count. In fact, he leads the Nationals in walks with seven and has a .353 on-base percentage entering Sunday's action.
There's another thing Acta noticed about Harris: He is great in the clubhouse.
"He has done very good," Acta said. "He gives me a lot of options. He looked real good in center field [on Friday]. He brings a lot of energy, which is something that I like. He is a perfect National League player."
One will never hear Harris complain about his role as a utility man. He is philosophical when he talks about his chances of being an everyday player.
"Everybody wants to play every day, but it can't happen," Harris said. "You have to have some guys who are able to play everywhere and do the little things. You just have to know what every role is, and you have to accept it.
"You have to keep pulling for your teammates and move on. Around the course of the season, all types of things could happen. You have to stay humble and get in your work. There are so many people in this game that can do things better than I can, and I can accept that. Everybody is not the same."
It looked like Harris would be an everyday outfielder when he was drafted by the Orioles in 1999. Two years later, he was the organization's Minor League Player of the Year. However, the Orioles traded Harris to the White Sox for outfielder Chris Singleton in January 2002. Chicago saw him as a utility player, and he played the role well during his four years there.
His biggest highlight came in the 2005 World Series against the Astros. Harris scored the winning run in Game 4 after leading off the eighth inning with a pinch-hit single in the White Sox's series-clinching 1-0 victory.
Harris credits manager Ozzie Guillen for teaching him how to be a valuable reserve.
"He really taught me how to play the game of baseball -- make different transitions and adjustments," Harris said. "The scoreboard dictates what a guy like me has to do. I'm not going to hit you 10 home runs. I'm not going to hit you five.
"If I need to steal a base, the scoreboard will let me know. If I need to take a strike or work out a walk, the scoreboard will let me know. I don't need a coach to tell me to take a strike. When you are playing the game, you should know what's going on and accept it."
Harris left the White Sox after the 2005 season and signed with the Red Sox. He didn't have much success in Boston, but he became a valuable player with the Braves in '07, hitting a career-high .270 with 32 RBIs in 117 games.
"It really worked out for me in Atlanta once I changed my batting stance," Harris said. "I went to a no-stride approach."
Harris has taken that hitting approach to the Nationals and hopes to stick as a utility player.
"[Playing different positions] makes you believe that I have a good shot at making the team," he said. "I can play [almost] everywhere."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.