The Red Sox acquired left-handed pitcher Javier Lopez from the Chicago White Sox on Thursday in exchange for righty David Riske with hopes of bolstering a bullpen that's missing an injured Keith Foulke.
Lopez, 28, who was picked up by Boston in the Rule 5 Draft in December 2002, was traded by the club to Colorado in March 2003. General manager Theo Epstein said a thorough scouting report by the Red Sox showed that Lopez has shown tremendous improvement since then.
"We thought that [Riske] was relatively expendable in order to get a lefty that we had a good, recent look at, who we think can help us now," Epstein said during a Thursday conference call. "In the long run, I think, looking forward to the second half of the season and beyond, clearing up a bit of that logjam with a redundancy of right-handed relievers will help us get a look at some younger guys who we want to see pitch in the big leagues."
In 26 appearances with Triple-A Charlotte, Lopez went 2-1 with a 0.55 ERA and 12 saves. He did not allow a run in his last 9 1/3 innings over eight appearances. He held left-handed batters to a .171 batting average.
In his big-league career with the Rockies and Diamondbacks, Lopez is 6-4 with a 6.09 ERA. He's allowed 22 percent (26-of-118) of inherited runners to score, and he's held left-handed batters to a .246 average.
Epstein said Lopez's fastball has a range of 85-90 mph, and he throws an above-average slider.
"He's still primarily a guy who's a very uncomfortable at-bat for left-handed hitters, but he's been much more affective against righties," Epstein said.
"I think with the way our bullpen has evolved, there's certainly a role for someone like that right now."
In eight relief appearances with the Red Sox this season, Riske went 0-1 with a 3.72 ERA. He was on the disabled list from April 12-May 22 with a lower back strain, and he pitched in just one game in the last 10 days. The right-hander had been acquired from Cleveland in a six-player trade in January.
Jason Brummond is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.