Lopez gives the Bucs a left-handed relief option they did not previously have. With the recent exit of Phil Dumatrait and the club's preference to have Donnie Veal begin next season as a starter in the Minors, Lopez immediately becomes the lone southpaw reliever on the Major League roster.
Lopez made his Major League debut in 2003, but he spent most of last season pitching with Triple-A Pawtucket. In the 14 appearances he made with the parent Red Sox in 2009, Lopez allowed 12 earned runs in 11 2/3 innings. These struggles, however, were a stark contrast to his success in Boston from 2006-08.
During that three-year span, Lopez, 32, made 158 appearances and posted a combined 2.70 ERA. So what happened in 2009 that got him a bit off track?
"I think it was the unpredictability of Major League relievers," answered general manager Neal Huntington. "They tend to have some good years and tend to have some bad years. Our guys saw some of the same things that made him effective in 2007 and '08 and feel like he's a definite candidate to bounce back next year."
During his time in Triple-A in 2009, Lopez fared just fine, going 1-1 with a 3.18 ERA in 38 relief appearances. He struck out 23 and walked 13 in 39 2/3 innings.
The Pirates are hopeful Lopez can be more than a left-handed specialist, as he has had decent success in getting right-handed hitters out throughout much of his time in the Majors. Over his seven-year career, Lopez has held left-handed hitters to a .247 average, while right-handed batters have hit him at a .295 clip.
"His arm slot makes him deceptive to left-handed hitters," Huntington said. "A good changeup and the fastball make him effective against right-handed hitters. He has the weapons to get right-handed hitters out."
Lopez was originally taken by the D-backs in the fourth round of the 1998 First-Year Player Draft but was traded to Colorado in '03. He made 142 appearances for the Rockies from 2003-05, including a career-high 75 in his rookie season.
Lopez has been added to the Pirates' 40-man roster, which now stands at 39. Despite giving Lopez a Major League contract, Huntington noted that Lopez is not guaranteed one of the bullpen vacancies simply because of the deal he signed.
"He'll have to earn it," Huntington said. "We gave him the Major League contract, and depending upon what else comes together, we'll see what happens."
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.