ARLINGTON -- Rockies shortstop Troy Tulowitzki returned to Denver on Friday and did some walking for roughly 25 minutes after undergoing surgery to remove scar tissue from his left groin Thursday in Philadelphia.

Tulowitzki hasn't played since May 30 and will likely miss eight more weeks.

In other injury news:

• Right-hander Juan Nicasio, recovering from a left knee strain that he suffered May 22, threw 60 pitches on Friday. His next step will be facing hitters next week.

Helton feels OK, says he's thinking too much

ARLINGTON -- Rockies first baseman Todd Helton being dropped one spot in the batting order Friday night against Texas had more to do with Interleague Play than his 2-for-13 hitting during this road trip, manager Jim Tracy said.

Jason Giambi served as designated hitter and batted fourth against pitcher Roy Oswalt, a former Astros star making his Rangers debut. Michael Cuddyer hit fifth, followed by Helton.

"Putting an extra left-handed bat behind [Carlos] Gonzalez filters Cuddyer down one and Todd down one, so the only reason that comes into play we have the DH tonight," Tracy said.

The current slump and Helton's overall stats -- a .234 batting average, with seven home runs and 32 RBIs -- raise questions about the health of his back, which has given him trouble for several years. Every stiff-looking run and swing, and every violent dive he makes trying to field a ball defensively, conjures questions about his health. Helton, 38, said his problems are more mental than physical.

"I've got different thoughts going through my head, just too many of them," Helton said. "I need to get one thought, stick with it and start hitting the baseball.

"I don't feel great, but I don't feel bad. I'm still physically able."

Addressing whether Helton is healthy, Tracy said, "I've not heard anything to the contrary and if he wasn't, I think I would have."

Herrera activated, plays short to spell Scutaro

ARLINGTON -- The Rockies activated Jonathan Herrera from the disabled list, after he missed 26 games with right hamstring and right shoulder injuries, and started him at shortstop to offer veteran Marco Scutaro a mini-break.

Scutaro, 38, came into the season as the second baseman, but started 19 straight games at short because of Troy Tulowitzki's injury in his left groin area. Tulowitzki underwent surgery Thursday and is expected to miss another eight weeks. Having Herrera, considered to have the range to play short, helps ease the wear and tear on Scutaro. The Rockies plan to rest Scutaro on Saturday.

Herrera took the roster spot of DJ LeMahieu, who was optioned to Triple-A Colorado Springs.

During a rehab assignment at Double-A Tulsa, Herrera had a hamstring setback, then experience soreness in his throwing shoulder before completing the rehab. Herrera went 3-for-17 in five games for Tulsa.

Before the injury, Herrera was batting .239 with two home runs, three doubles and four RBIs while playing all over the infield. His presence increases the team's defensive versatility. Friday's starting lineup is likely a preview of the players who will be on the field when the Rockies need defense. Chris Nelson moved from second base to third base and Jordan Pacheco rested; in close games, Nelson has been moving to third in late innings.

"I'm able to play second, short or third base," Herrera said. "I don't have any position that I'm not comfortable at. The last couple of days, I played short. I have to be able to play anywhere the team needs me."

Rosario learning on the fly, faring quite well

ARLINGTON -- Rockies manager Jim Tracy is closely monitoring playing time of many of his veterans, so he's happy to have spry, young rookie catcher Wilin Rosario.

Tracy started Rosario on Friday night against the Rangers for the sixth time in seven games on the road trip, and it was Rosario's 39th start. He has started all but six of the 26 games since Ramon Hernandez went to the disabled list with a left hand strain.

Rosario entered Friday leading Major League rookies, as well as National League catchers, in home runs with 11, and his 32 RBIs put him ahead of all other Major League rookies. The Red Sox's Will Middlebrooks trailed him by one.

Tracy said Rosario, 23, will take a break Saturday afternoon, but wear and tear is not an issue. Tracy said the amount of playing time Rosario has been forced to eat up has helped his learning curve.

"This is not a problem," Tracy said. "There is no greater teacher than exposure. We can sit here and talk about it, but that's not going to replace the guy actually going out there and having to deal with the game. You have a game plan for a specific hitter, the game plan starts to unfold, the hitter gets to two strikes, he fouls two or three pitches off. Do you have the wherewithal to understand what the swings are telling you and what the next place is that you have to go?"