The Chicago White Sox had one of the worst bullpens in baseball last season, but on Tuesday they made a big step forward in trying to address that issue as they signed relief pitcher Zach Duke to a three-year contract worth a reported $15 million.

Duke, who started his career as a starting pitcher for the Pittsburgh Pirates before moving to the bullpen in 2011 with the Arizona Diamondbacks, had a really strong 2014 season for the Milwaukee Brewers. His 2.45 ERA in 74 appearances is impressive enough, but his Fielding Independent Pitching mark of 2.14 was far and away the best of his career. Duke also struck out 11.4 batters per nine innings, another career high, and best of all for the White Sox, he was able to remain healthy after suffering from various injuries over the past few seasons.

That trend of getting injured is one that the White Sox are surely going to have to be careful of, but overall it’s a solid signing. Left-handed pitching is difficult to find in baseball, and when you have the kind of strikeout numbers that Duke had last season, it’s hard to ignore that kind of performance. What really set him apart was a tweak to his delivery, which saw him throw the ball with more of a sidearm motion. The results are evident as his strikeout totals skyrocketed, and it will be interesting to see if he can continue to build upon his success from last season.

With Matt Lindstrom hitting the free agent market and guys like Javy Guerra not exactly providing shutdown stuff at the back end of the Sox pen, Duke will be a welcome addition as Rick Hahn tries to take the team from AL Central afterthoughts to potential contenders.