The term "battle of the bullpens" gets thrown around a lot these days, but it certainly applies this weekend when the Kansas City Royals visit the Baltimore Orioles.

Kansas City's Greg Holland has 30 saves. Baltimore's Zach Britton has 32. And both are supported by strong groups of relievers who combine to form two of the top four bullpens in baseball.

At the plate, the Orioles produce runs in a much different fashion from the Royals. Baltimore muscles up, led by first baseman Chris Davis, who has a major league-high 41 homers. Kansas City, led by catcher Salvador Perez's 19 dingers, is not nearly as prolific with the long ball.

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A prime example of that point from the Royals' perspective is designated hitter Kendrys Morales, who has crossed the century mark in RBIs despite hitting only 17 home runs. The difference between his RBIs and homers -- or his number of "teammates driven in" -- leads the majors this season.

Danny Duffy gets the start for Kansas City in tonight's series opener. An interesting trend to keep an eye on is the number of outs he records on groundballs. It usually isn't many, at least compared with other left-handers.