Gutierrez will have an MRI test when the team returns to Seattle on Thursday, and manager Eric Wedge said no timeline could be put on his recovery until then.
The 2010 Gold Glove outfielder is making his fifth trip to the disabled list in the past three seasons. He played only 132 games combined in 2011-12 because of a stomach disorder, a strained oblique, a torn pectoral muscle and a concussion. Now he is out with a hamstring strain after diving for a bloop single in the fourth inning of Monday's 7-1 win over the Astros.
"There's been players that have been snake bit before, and I do think he's one of the most unlucky guys I've had the fortune of being around," Wedge said. "But everybody has tried everything under the sun to help him be on the field more.
"Whether it's body type or bad luck or whatever it may be. He's playing center field and having to react to every ball; there's a lot to be said for that. There's nothing that hasn't been looked at with him, and it's just unfortunate. I feel bad for him and for us."
The 6-foot-5, 260-pound Peguero is not a candidate to play center field, but he can fill a backup corner-outfield spot. Peguero has hit .191 with eight home runs and 26 RBIs in 63 games in limited duty with Seattle over the previous two years.
Endy Chavez will handle the bulk of center-field duties, with Jason Bay available as a backup option until Saunders returns. Bay has played 38 games in center field in his Major League career, but none since 2005 while with the Pirates. He did play two games there this spring in Cactus League games for the Mariners.
Saunders is eligible to come off the 15-day DL on Friday.
Peguero has been working on better patience at the plate and has drawn 11 walks in his 17 games in Tacoma. He would just like an opportunity to show what he has been working on.
"Each of the times I've come up and been sent back down, it's something to learn," Peguero said. "It's just understanding what I have to do as a player, understanding why they're bringing me here and what kind of player I am and show them that I'm learning each and every day."
"He's been working hard on being more disciplined and not chasing outside of the zone and being willing to take those walks," Wedge said. "As big and strong as he is, he does scare people up there. If you chase, it kind of defeats the purpose. But he has been better with that."