Hahn's groundballin' bullpen

Rick Hahn's transformation of the bullpen didn't take long. While the White Sox were quiet last offseason, one signing late in the offseason gave the White Sox GM the opportunity to reveal his plan for his relievers.

The official announcement of Matt Lindstrom's signing came at SoxFest 2013. Looking back on my notes, Hahn had a couple themes he was pushing. First, pitching was a priority for him ("You need an elite pitching staff to compete in the AL Central and in our ballpark."). Second, he wanted groundball pitchers ("Lindstrom is a power arm with sink and he keeps the ball in the park."). See if you notice a trend in reliever GB%:

*lower threshold than '12 so as to capture traded players

There is debate over the effectiveness of groundball pitchers. Rob Neyer summarizes sabermetrics elder statesman Bill James' thoughts on the subject - such pitchers are overrated - but that analysis appeared to be aimed at starting pitchers.

In any event, there is the intuitive logic that, in a park that rewards hitters that put the ball in the air, it's a good idea to keep the ball on the ground. There are obviously a few sample size issues with the last table. Petricka and Webb in particular have very limited MLB data. Petricka, though, has the minor league background to back up something approaching that 62.9%. Webb, on the other hand, uses a four-seamer more than his sinker and historically has been well below 50%.

But the trend is clear. Reed, a pretty extreme fly ball pitcher, was traded away. Crain, another extreme fly ball pitcher, was, too (though obviously for reasons unrelated to his batted ball tendencies). Axelrod, a flyball pitcher who also threw a lot of innings as a starter, was non-tendered. In their place, one of the most extreme groundball pitchers in baseball in Belisario, a guy who was never below 51% at any level in Petricka and a guy who has the repertoire to get groundballs in Webb. And, to replace Thornton, who in his career did a good job inducing groundballs, Hahn gets Downs, whose 9th place ranking in GB% since 2009 is a nice complement to Belisario, the man in 3rd place.

The holdovers, Lindstrom and Jones, were in the top half of the list in 2013 but now find themselves at the bottom for 2014. Lindstrom's career numbers, however, are skewed by his pre-2012 pitch selection, in which he heavily featured his four-seam. He now throws his sinker more, resulting in GB% over 50% each of the last two seasons. Jones throws his sinker more than half the time and his uptick in groundballs in 2013 is likely sustainable.

Of course, to maximize the benefit, good infielders are necessary. As I've noted in the past, Alexei Ramirez and Gordon Beckham are excellent at turning two, so there's something to be exploited there. Ramirez rates well on defense by nearly any measure but Beckham draws more mixed (and certainly less enthusiastic) reviews. We have no real idea how Abreu will be at first. The acquisition of Matt Davidson points to him being the long-term plan at third and he doesn't get much better than okay reviews on defense.

It takes time for a GM to put his stamp on a team. Hahn's on his way with the starting pitching and the offense but he's revamped the bullpen, for reasons both idiosyncratic to the White Sox (expiring contracts) and general (relievers largely fungible), in basically a calendar year.