OAKLAND -- Jim Johnson has never pitched for a big league team other than the Baltimore Orioles, and when the week began, he had no reason to think that was about to change.

But when Johnson, traveling Monday from Florida to Southern California for a players' union meeting, got off his flight, his phone was crawling with missed calls, voicemails, texts and tweets.

The owner of back-to-back 50-save seasons had been traded to the A's.

"The first thing I thought of was not baseball but how it would affect my family," said Johnson, who has spent all eight of his major league seasons with Baltimore. "This was the first and only place I'd been, and this was something new.

"Then I started to look at the team. Even after my deal, they were making more moves," he said, referring to the acquisitions Tuesday of outfielder Craig Gentry and reliever Luke Gregerson.

"They've picked up some pretty good players today. I'm excited to be part of that.''

Johnson, 30, a 6-foot-6, 230-pound right-hander, is arbitration eligible and stands to earn more than $10 million next season unless the A's reach agreement with him on a new deal.

"Jim Johnson comes with a pretty big price tag," third baseman Josh Donaldson said. "But he's part of (general manager) Billy Beane trying to create the right mix.

"Johnson has that power sinker and big hammer of a curve. He's a guy who's going to get a lot of ground balls. I'm hoping he'll get me a few more double play grounders."

In Johnson, the A's are getting someone who, except for a rough patch early in 2013, has been one of the toughest pitchers to face in the ninth inning. He calls his form of closing "grinding," and says he expects it will translate well to the West Coast.

"From the other dugout there were always a couple of places where you knew it would be a dogfight, and Oakland was one of those," Johnson said. "Those are the type of teams that do well, and there's nothing I'm not used to."

The addition of Johnson and Gregerson represent an upgrade for the A's bullpen, despite the loss of closer Grant Balfour.

"When you lose a guy like Grant, who's been real good for us for three years, you'd be foolish not to consider (trading for Johnson)," Beane said. "And getting Luke lightens the load on everybody. These moves have made us potentially better. The next step is to put it on the field.''