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6/8/2014 2:11 P.M. ET

Joseph's defense catching on behind plate

BALTIMORE -- Caleb Joseph arrived in the Major Leagues with a stronger reputation at the plate than behind it. He's finally starting to come on a bit as a hitter, but in the meantime, Buck Showalter has been impressed with the way the catcher has handled himself defensively.

The catcher has yet to make an error in 15 games and has thrown out 40 percent of attempted basestealers.

"I think he understands his priority is throwing better," Orioles manager Buck Showalter said. "Some things that John Russell and [Joseph] did at Spring Training with Donnie Werner really seems to have helped him some."

Joseph was named the Eastern League Player of the Year in 2013 after batting .299 with Double-A Bowie and was hitting .261 with a .404 slugging percentage in 22 games with Triple-A Norfolk this year before being called up on May 7.

His time in the Majors started slow -- his average sat below .100 at the end of June -- but in five games this month he's gone 4-for-15 and lifted his average to .136.

During Saturday's 6-3 win against the Athletics, Joseph drove in the first of Baltimore's three runs during the fifth inning on a double against starting pitcher Sonny Gray.

"I still think Caleb's going to hit a little bit, which he has," Showalter said. "He's gotten some big hits for us."

On Saturday, Joseph was also behind the plate for Kevin Gausman's first win as a starting pitcher. The two played together in Norfolk for the first month of the season, before Joseph got the call to the Majors.

That familiarity helped the battery. Gausman, who typically throws four pitches, didn't use his circle changeup at all on Saturday and put together the best start of his career.

"That was the thought behind it last night," Showalter said. "I wanted Nick Hundley to see Gausman before he caught him. Of course, a lot of catchers can look real smart when Gaus is carrying that stuff. Is there really a bad finger to put down?"

Hunter activated from DL for series finale vs. A's

BALTIMORE -- After one rehab appearance in the Minors and just 11 pitches on Saturday night, Tommy Hunter was back at Oriole Park at Camden Yards on Sunday and available to pitch in the series finale against the A's.

Hunter struck out two batters and had a hit batsman with a caught stealing during his brief outing for low Class A Delmarva on Saturday. He threw eight strikes and three balls in his first outing since hitting the disabled list on May 22 with a groin strain.

"I felt good," Hunter said. "I was able to throw the ball over the plate for the most part -- except the last guy."

To make room for Hunter on the 25-man roster, the Orioles optioned right-hander Evan Meek to Triple-A Norfolk prior to Sunday's game.

Hunter started the season strong for the O's, converting 11 of his first 12 save opportunities, although he allowed an earned run in four of them. But Hunter blew his final two save opportunities and saw his ERA balloon to 6.06 during his final four appearances before landing on the DL.

"I don't think rest physically was needed, but potentially and hopefully a little mental break might help," Orioles manager Buck Showalter said. "I think a lot of times when you can kind of reset with guys, especially pitchers, sometimes you get a guy who pitches more like his track record suggests."

Hunter posted a 2.81 ERA in a career-high 68 appearances last season and took over the full-time closer role at the start of this season. Zach Britton has taken over as Baltimore's closer since Hunter blew his last save against the Tigers on May 13.

Hunter has battled groin injuries in the past and has spent two extended stints on the DL because of them, but he says there's nothing special he can do about it this time around. He's just going to keep stretching it out and make sure he stays well rested.

"Once you get hurt, you're bound to hurt it again," Hunter said. "This is like the fourth time with it, so I keep doing it and keep stretching. There's really not much you can do."

Worth noting

• Reliever Darren O'Day was unavailable on Sunday after pitching 1 2/3 innings on Saturday and an inning on Friday. Showalter intentionally avoided using Britton in relief on Saturday so he would be available for the series finale against the A's.

• Hunter spent his one rehab stint as part of one of the best pitching staffs in the South Atlantic League. Delmarva's 2.88 team ERA is the second best in the league. "Tommy said he felt some pressure there last night," Showalter joked before Sunday's game.

David Wilson is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.