Hamilton was in the starting lineup Friday night, batting seventh and manning the vast spaces in the park's outfield, which include Tal's Hill and a 436-foot distance to straightaway center.
On Friday afternoon, Reds manager Bryan Price said Hamilton had been "symptom-free for several days," making the outfielder available on the first day after his DL stint expired.
Hamilton missed eight games after being tagged in the head on a slide during Cincinnati's 12-7 loss to St. Louis on June 8. Hamilton said he felt cooped up while missing a week of games, with the team sporting a 9-6 June mark entering this series in Houston.
"You never want to go that many days without playing baseball," the Mississippi native said. "Just to have those days of rest was big, though, but you can't mess with a concussion. ... I feel like it's a new season already since I haven't played in so long."
Price said Hamilton, who has bumped his on-base percentage up by over 30 points this season, will be a versatile cog in Cincy's lineup.
"The weeks leading up to the injury, he had been swinging the bat really well and doing a lot of good things for us," Price said. "He adds a real nice dimension to our ballclub. It's definitely a lift in many different ways."
Hamilton was hitting .269 with two homers, nine RBIs and 16 steals entering Friday.
It was the third time Hamilton missed at least three straight games this season. The first was due to a thumb injury in April and the second because of a death in the family in May. He emphasized a different approach in staying sharp at the plate upon his return this time around.
"First couple times, I didn't see [the ball] well when I got [back]," Hamilton said. "I took more reps in the cage this time, watched some guys' bullpens just to see some pitches.
"After my nephew [died in May], I felt like I wasn't ready yet or prepared when I came back. ... This time, I feel like I'm prepared way better."
• The Reds signed their sixth-round pick in this year's MLB Draft, inking Tyler Mondile to a $309,700 deal. Mondile, a right-handed high school pitcher from New Jersey, will be assigned to extended spring training work in Goodyear, Ariz.
• Cincinnati and Pittsburgh will play a day-night doubleheader on Sept. 17 at Great American Ballpark to make up for their postponed game on May 10. Game times will be 12:10 p.m. ET (the makeup game) and 6:10 p.m., and tickets from the May 10 game will be valid for the afternoon contest.