SEATTLE -- Astros manager AJ Hinch said reliever Ken Giles hasn't pitched since Saturday because of a problem with his back.
"He's been battling a little bit of back tightness and had been unavailable the last couple of days,'' Hinch said before Thursday's series finale against the Mariners. "I had him up on Sunday [in the bullpen in Houston], but when we got to Seattle he reported a little bit of back soreness. It has progressively gotten a little bit worse to where he can't go yet."
Giles hasn't pitched in five games, so he could go on the disabled list, retroactive to Sunday.
"I don't know,'' Hinch said. "We don't want him to miss too much time. Right now, just given that he can't move around and do the things he normally does, it's a little concerning. But we haven't talked DL yet.
"Luckily our starting pitchers have gone deep into games, and I don't have enough innings for all our relievers, so Giles being down a few days hasn't impacted us."
Tough turf in Seattle
Some of the Astros have an issue with the new grass at Safeco Field. The Mariners replaced all the grass after last season, but the new turf has caused some problems with footing in the outfield, which could be weather-related.
"I know the weather hasn't cooperated for it to really take, and we've been in conversations with the grounds crew here,'' Hinch said. "They understand. With the weather, the cold, the roof, it hasn't taken form yet."
Hinch is sympathetic to the problems that come with new grass.
"There are some issues in the outfield, but both teams have to deal with it," Hinch said. "We are used to coming here and having it be pristine, and it's not there yet. I'm sure by the time we get back it'll be picture perfect."
Astros outfielder George Springer slipped and fell while trying to run down a fly ball Tuesday night, but he didn't want to make excuses.
"It's been a little bit of an issue,'' Hinch said. "We've had a couple of guys slip in the outfield. When the ball hits it. It kicks up a ton of sand.''
Outfielder Derek Fisher, who ran back to the wall to rob Jean Segura of a homer Wednesday night, said players need to be aware of the new turf.

"It's just about being careful and knowing where you're at," Fisher said. "It could be better, but I've never planted sod in my life. I know it's a little more difficult than any of us can speak on."