ARLINGTON -- If the Mariners are going to replace a struggling Felix Hernandez in the rotation for his Sunday start in Houston, it appears Erasmo Ramirez won't be an option, as manager Scott Servais said Wednesday that the right-hander likely will need another Minor League rehab outing this week.
Ramirez threw four innings on Sunday for Triple-A Tacoma in his fourth rehab start as he returns from a strained right shoulder that has sidelined him since May 1. After three very sharp outings, he allowed four runs (three earned) on six hits with two walks and four strikeouts against Colorado Springs at Cheney Stadium.
"I don't have the exact schedule," Servais said of Ramirez's upcoming plans. "But his last outing wasn't that sharp. By his own admission, he was off a little mechanically. It was more a timing issue. So he could get one more. It happens. Guys aren't quite on with all their stuff, so that's where that's at."
The Mariners are facing a tough decision with Hernandez, the longtime ace of the staff who has gone 8-10 with a 5.73 ERA in 23 starts this season and gave up a career-high 11 runs (seven earned) on eight hits with four walks and a hit batter in six innings in Tuesday's 11-4 loss to the Rangers.

The Mariners do have other options in Triple-A Tacoma if they want to call up a starter to take Hernandez's spot. Rob Whalen, who threw extremely well in a spot start earlier this season, started on Tuesday for the Rainiers, and he would be in line to start again Sunday on normal rest.
But Whalen has struggled of late himself since dealing with a sore right arm, and he allowed six hits and seven runs (four earned) in 3 1/3 innings on Tuesday.
Right-handers Casey Lawrence (7-3, 2.75 ERA in 15 games with 12 starts) and Christian Bergman (7-8, 5.35 ERA in 22 games with 21 starts) are scheduled to pitch Friday and Saturday, respectively, for Tacoma, and they could easily be held back until Sunday if needed. Both have pitched for Seattle in the past two years with mixed results.
Ramirez, 28, initially was slated to be in the Mariners' rotation this year until running into arm troubles in Spring Training. He has by far the most Major League experience among that group, but he'll need to show he's ready.
Ramirez acknowledged last week that facing aggressive Minor League hitters is good for building up endurance, but it isn't always the best test for his offspeed offerings since young players tend to swing at early fastballs. He'd racked up 12 strikeouts with no walks in nine innings while allowing just one run on five hits in his first three outings before Sunday.
"It can work good or bad, depending on what you have that day," Servais said of facing Minor League hitters. "But Erasmo does throw strikes. That's one of the reasons we like him and acquired him. That's when he's at his best as far as keeping the pitch count in check and doing those type of things. I haven't seen him throw, other than a little clip here and there on video, so it's hard to tell."
Injury updates
Two other pitchers on the 10-day disabled list -- lefty Roenis Elias and right-hander Dan Altavilla -- are both progressing with their throwing programs back in Seattle and are close to going out on Minor League rehab stints, Servais said.
Elias went on the DL on July 31 with a left triceps strain, and Altavilla has been sidelined for two months with a sprained right elbow.
Altavilla will need more time to build back up since he's been out so long, but he could be a potential September addition if he can get back to full strength. Elias is a potential starter or long man who could be back fairly quickly as he was playing catch last week at Safeco Field, after which he said his arm was feeling better.