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6/22/2013 10:19 P.M. ET

Jaso misses second straight game with hand injury

SEATTLE -- A left palm abrasion kept catcher John Jaso out of the A's starting lineup for a second straight day, though he was considered to be available off the bench if absolutely necessary.

"Between [the two catchers], I think it probably equates to having one and a half right now," manager Bob Melvin said. "But if he had to go back there, he could, even if I had to pick him up and carry him back there."

Jaso, who suffered the injury while sliding in Texas on Thursday, was a late scratch from Friday's game after experiencing significant pain in the hand while attempting to take batting practice. It wasn't any better Saturday, when Derek Norris received another start behind the plate.

"I don't know what kind of time it's going to take," Jaso said, "but I definitely can't swing. It hurts way too bad."

The timing of the injury is unfortunate for Jaso, who has reached base safely in 18 of his last 19 games, going 20-for-58 with 13 walks over that span for a .466 on-base percentage.

"Whenever you lose a hot bat, a guy that's on base all the time," Melvin said, "it does affect things some."

Norris looking to be more aggressive with bat

SEATTLE -- With John Jaso unavailable again Saturday because of a palm abrasion, Derek Norris was sent back out behind the plate in Seattle.

So was his .189 average -- against a right-hander in Aaron Harang, no less.

Norris, hitting .132 vs. right-handers compared to .241 against lefties, enjoyed a productive April, hitting .283 overall, but since the start of May, he is 17-for-113 (.150). His struggles aren't as noticeable to teammates who praise his defensive doings, but they are a concern.

"Obviously he's struggled some and every time he does hit a ball hard it's right at somebody," said manager Bob Melvin, who also noted shifts have come into play. "You go through struggles during the season and you can't let it affect you, especially in the job he has to do, and he hasn't.

"It's frustrating for him, especially being a guy that, for the most part of his career, has been looked at as offensive-minded. That tests you a little bit, but he's doing a nice job behind the plate."

Norris recently said he's been trying to free up his hands because, at times, he said, "I feel a little locked up and I'm not finding the barrel as much as I want to.

"I'm looking to make a few changes. I obviously haven't gotten to the best start I wanted to this year, and it shows, but I'm looking to make a change. There's a few mechanical changes I've worked on, trying to be a little more confident, a little more aggressive at the plate, not being so passive."

Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.