Zach Duke excelled at keeping the ball down in 2014.What are the White Sox getting in Zach Duke?

From our viewpoint, he was the second-best left-handed relief option available in free agency, behind Andrew Miller.

The 31-year-old Duke excelled in relief for the Brewers last season, posting a 2.45 ERA, with 74 strikeouts and only 17 walks in 58 2/3 innings pitched over 74 appearances.

Duke had previously pitched for the Pirates, Diamondbacks, Nationals and Reds but had never been able to perform at a level anywhere close to that which he did as a rookie in 2005, when he had a 1.81 ERA in 14 starts, until last season.

Zach Duke- Last 4 Seasons

Duke changed things up prior to 2014 in two ways, dropping his arm slot to a siderarm delivery and increasing the use of his breaking pitches at the expense of his changeup (as this article thoroughly details).

That led to a sharp spike in his ground-ball rate and made him much tougher to hit home runs against. It also raised his strikeout rate to a level previously unseen in his career.

Duke handled both left and right-handed batters without issue with this new look. Lefties hit .198 against him. Righties hit .242. His opponents' slugging percentage was terrific- .302 against lefties, .298 against righties.

A look at the heat map atop this article shows where Duke most frequently threw pitches in 2014. He had the second-highest rate of pitches thrown in the lower-third of the strike zone or below among anyone who threw at least 50 innings (68 percent), trailing only submariner Brad Ziegler.

Steamer's projections for 2015 don't anticipate Duke replicating his 2014 success, but they don't project him to have a huge drop-off either. They put his ERA for 2015 at 3.10 and keep his strikeout-to-walk ratio at 3.5-to-1.