CHICAGO -- The A's placed infielder Eric Sogard on the 15-day disabled list with a strained back, a move that cleared a roster spot for Friday starter Brandon McCarthy.

Sogard said he first felt his back stiffen while taking batting practice on Monday and, after not feeling any improvement in the days that followed, consulted with the A's and decided it best to shut things down for a while.

Sogard, who said he experienced similar discomfort in his back for a short time last season, will fly to Arizona on Saturday to begin rehab.

Since being recalled from Triple-A Sacramento on July 20 for his third stint with the A's this season, the infielder was 7-for-33 (.212) in 15 games.

Depth being used to rest Milone, Parker

CHICAGO -- Taking full advantage of their enviable pitching depth, the A's are mixing up their rotation for the coming week in an effort to provide youngsters Tommy Milone and Jarrod Parker extended rest.

Milone, originally slated to pitch Saturday in Chicago, won't go until Aug. 17 for the club's opener against the visiting Indians, while fellow rookie Parker, first scheduled to throw in Sunday's series finale against the White Sox, will take the mound Tuesday in Kansas City.

In need of a starter for Saturday, the A's looked no further than lefty Travis Blackley, who has provided a steady hand in both the rotation and, more recently, the bullpen. Bartolo Colon, meanwhile, will stay on a five-day schedule and pitch against his former Chicago squad on Sunday.

That leaves Dan Straily on track to start Wednesday, having also garnered one extra day of rest, and Friday starter Brandon McCarthy in line to go again Thursday on five days' rest. Should he be unable to do so, if he experiences more issues with his right shoulder, Blackley could go again in his spot.

"We've been looking for a way to try to give Parker and Milone a little bit of a break," A's manager Bob Melvin said. "We are very cognizant of the workload of our younger pitchers, and we feel like this is a good time to be able to give them a little bit of a break, refresh them going forward for the rest of the season.

"It's a mental grind once you get to this time of the year. Tommy's last few games haven't been his best, but it really isn't about that. We've been looking to potentially do this for a while now, and with the two off-days and McCarthy coming back and the way Travis has pitched for us, this worked out very well timing-wise. It's about giving them a break."

Milone, already up to 140 1/3 innings this season, acknowledged his struggles on Friday in Chicago, and he referenced a similar stretch last season that was helped along by extra rest. The lefty has allowed at least five runs in each of his last three starts, after giving up more than one just twice in his previous six outings, twice not surrendering any.

"I had a couple of rough starts in a row around this same time last year, and they felt it was probably a good idea for me to rest because I hadn't skipped or missed a start before," Milone said. "After that, I came back and felt a lot better.

"For me to be pitching the way I am is obviously frustrating, and it could be a mechanical thing, just because I'm trying to fix things to make it how I want them to be, and rest may be just what I need, rather than changing things. I can definitely tell there's a difference when I'm out there. The pitches I'm throwing are just off. I feel the same, but it's just not coming out the same."

Parker, meanwhile, has gone 2-3 with a 5.94 ERA since sitting with a 5-3 record and a 2.46 ERA on July 2. Time off should also serve him well, and the team's ability to give that to him speaks volumes about its depth. Rehabbing hurlers A.J. Griffin and Brett Anderson are also expected back soon.

"We wouldn't be able to do this without the depth," Melvin said. "It means we have depth in starting pitchers a lot of teams don't have and we have confidence in quite a few of them and rightfully so."

Worth noting

• Outfielder Seth Smith, on the disabled list with a strained left hamstring, has begun hitting off a tee and is progressing nicely, A's manager Bob Melvin said. Smith is eligible to be reinstated on Aug. 18.

• Brett Anderson, making his fifth rehab start Friday, allowed just three hits in six shutout innings for Triple-A Sacramento, striking out four and walking one in Oklahoma City. He threw 80 pitches, 47 for strikes, and is expected to make at least one more rehab start in the Minors before the club determines his readiness for Major League action.