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7/6/2014 12:30 A.M. ET

Lefty Roth gets a chance to work out of bullpen

ANAHEIM -- Michael Roth learned how to be a relief pitcher nearly 15 months ago.

Last April, the left-handed Roth entered a 4-2 game in Minnesota with runners at second and third in the fifth inning. Left-handed Oswaldo Arcia was the batter and Roth had to deliver a slider right away instead of working his way into the game. Roth got Arcia to fly out to escape the inning.

"That very first pitch you have to be right on," Roth said. "You're coming in with men on base maybe, so that first pitch means something right away. I learned that last year."

After starting 14 games with Double-A Arkansas, Roth was called up to the Angels on Saturday to bolster a bullpen that now has two left-handed arms. In 2013, Roth appeared in 15 games for the Angels during three separate stints and posted a 7.20 ERA in 20 innings.

"Last year was kind of a learning year for me, learning what I need to do to be prepared to come out of the bullpen versus being a starter," Roth said.

Roth dazzled in Arkansas, going 7-4 with a 2.40 ERA in 90 innings.

"He's definitely found his rhythm and delivered and he's having a great year down in Double-A," Angels manager Mike Scioscia said. "We know his makeup is great and, hopefully, it'll translate into when he gets an opportunity up here to have better results."

Roth, 24, last started on Sunday for Arkansas, tossing six innings of one-run ball.

Reliever Cory Rasmus was optioned to Triple-A Salt Lake to make room for Roth, who made his season debut in Saturday night's 11-5 victory. Roth picked up the win after tossing two perfect innings with two strikeouts in relief of Hector Santiago.

Angels look for Thatcher to fill void in bullpen

ANAHEIM -- For Joe Thatcher, he's been in this situation before.

He's heard his name whispered in trade rumors and he's seen his name floated as a bargaining piece. But the Angels made those rumors reality when they acquired the veteran left-handed reliever Saturday for two prospects.

Last season, Thatcher was dealt from the Padres to the D-backs hours before the July 31 non-waiver Trade Deadline. So what was his reaction to Saturday's move?

"I was surprised," Thatcher said. "I kinda assumed the same thing [as last year] would happen again, so I'm surprised they traded this early before the Deadline, but the sooner I get over here, the better."

Thatcher appeared in 37 games out of the bullpen for Arizona, posting a 2.63 ERA and an 8.33 strikeout-to-walk ratio. He has not walked a batter since April 29 and has only given up two hits since June 8.

The 32-year-old has been tough on lefties, allowing them to hit just .221 against him in his career. This season, left-handed hitters (.241) have posted similar numbers to right-handed hitters (.256).

"He's funky, he's tough to pick up, he makes left-handers very uncomfortable and he's also capable against a righty," Angels general manager Jerry Dipoto said. "He's not a guy who has to be a situational, one-on-one left-hander."

Dipoto said the Angels liked Thatcher's ability to throw strikes, limit walks and strand inherited runners. Thatcher has issued just three walks all season, thrown 72.4 percent of his pitches for strikes and allowed only eight of 37 inherited runners to score.

"When you're looking to clean up that inning with runners on base and get the key out with a left-handed hitter, it's something we've been missing all year long," Dipoto said. "We just haven't had it.

"Joe Thatcher is our shot at an answer."

The Angels bullpen has been the primary focus of Dipoto in the last eight days, orchestrating three trades for relief pitchers. He acquired Jason Grilli on June 27 and Rich Hill on Tuesday. Hill was designated for assignment Saturday to make room for Thatcher.

But Saturday's move could be the last for the Angels, whom many were anticipating to be big Deadline players.

"I don't know how much more tweaking we'll need to do," Dipoto said. "We're not anticipating making a move in any other [non-bullpen] area."

Manager Mike Scioscia said Thatcher would primarily be used as a left-handed specialist but could absorb more innings later.

"We're trying to get some depth and balance in both sides of our 'pen and it keeps evolving and I think we are making strides and getting better down there," Scioscia said. "This will be one big piece that will definitely take the load off some guys that have been pitching a lot and that's a concern, too."

The Angels also added outfielder Tony Campana in the trade that sent outfielder Zach Borenstein and right-hander Joey Krehbiel to Arizona. Campana, 28, has spent most of the season at Triple-A and was optioned to Salt Lake on Saturday.

The D-backs began the day with the worst record in baseball (36-53) and 13 1/2 games out of first place in the National League West.

"Come to a winning ballclub and be in a pennant race, that's what we all play for, so it's exciting," Thatcher said. "I'm excited to come here and get thrown fire right away and help contribute in any way I can."

Angels focused on improving own ballclub

ANAHEIM -- Despite chasing the American League West-leading Athletics, Angels general manager Jerry Dipoto's reaction to Oakland's trade was likely no different than many fans.

"My initial reaction was, 'Wow,' like I'm sure every other person in baseball or fan watching," Dipoto said.

On Friday, the A's acquired right-handed starters Jeff Samardzija and Jason Hammel from the Cubs in exchange for Minor Leaguers Addison Russell, Dan Straily, Billy McKinney and a player to be named. Both Samardzija and Hammel sport sub-3.00 ERAs and will add to a pitching staff that already leads the AL in ERA.

"I'm sure they're very happy with it," Dipoto said.

The Angels, who entered Saturday 3 1/2 games behind Oakland, made a move of their own Saturday, acquiring left-hander Joe Thatcher and Tony Campana from the D-backs for two prospects. While some may view the Angels' trade as a response to Oakland, Dipoto said the deal was finalized Friday afternoon.

"We can only control what we can control and what we've identified that we want to focus is what we've been working and that was to change the look of the bullpen and so far, we've been able to accomplish that," he said.

Manager Mike Scioscia said he does not pay much attention to midseason trades, instead turning his attention toward his own club.

"We have enough on our plate to focus on than to worry about what other clubs are doing," Scioscia said. "Every club's going to be tough. Just like other clubs are going to improve, we need to improve. … We want to keep these pieces together and continue to play well as a team."

The Angels are 3-6 this season against Oakland and will face the new-look A's for the first time on Aug. 22.

Worth noting

David Freese was held out of Saturday's lineup with a sore shin that he injured sliding into home during Friday's win. John McDonald started in Freese's place, hitting ninth.

Freese pinch-hit for McDonald in the seventh inning and hit a two-run homer during the Angel's eight-run, game-changing rally.

• Reliever Fernando Salas will make another rehab appearance Sunday for Class A Inland Empire. Salas made his first rehab appearance Friday, tossing one inning of scoreless ball with one strikeout.

Salas, who's been out since June 15 with shoulder inflammation, is "close" to returning, Scioscia said.

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