When the D-backs signed veteran reliever Tyler Clippard to a two-year deal on Monday, general manager Dave Stewart made it clear that Clippard was brought in to support closer Brad Ziegler, not supplant him. For those of us who like oddities in our world, this is good news: Ziegler will remain baseball's most unexpected closer.
No, really. There's no one working the ninth inning in baseball like Ziegler right now, and there hasn't been for years. In an era where flamethrowers like Aroldis Chapman and Craig Kimbrel are lighting up radar guns, Arizona's closer averages 84.6 mph on his primary pitch and has a near pathological aversion to strikeouts, finishing in the bottom 30 (of the 268 pitchers with a minimum 60 innings thrown) in both K/9 (4.76) and K% (13.7).
Being a submariner on its own sets Ziegler apart. But it gets particularly interesting when we look at where he lands on a comparison of spin vs. vertical movement for fastballs (defined for these purposes as four-seam, two-seam, and sinker). We learned in the first season of Statcast™ that there's a relationship between spin and batted-ball outcomes, and that's largely because there's a relationship between spin and movement:

It's not a perfect relationship, because not all spin is useful spin, but it's there -- for the most part, if you throw your fastball with a higher spin, you get more vertical movement, which is another way of saying "the ball defies gravity for slightly longer and stays up."
But you'll also notice that some pitchers have negative vertical movement, which is to say that the ball breaks downward, and very few pitchers can achieve that. In fact, it's all but impossible if you're throwing from a traditional arm slot, and the five names below that line (Joe Smith, Justin Masterson, Darren O'Day, Peter Moylan, and Ziegler) are all sidearm or submariners.
Intuitively, that should make sense. While a submariner doesn't actually release the ball out of the hand differently than a traditional pitcher, they're bent so far over at the waist that the end result is that the spin angle is all but inverted, making the spin something more like a curveball (which has topspin driving the ball down) than a fastball (which has backspin).
Gif: Brad Ziegler sinker
Naturally, that movement is how Ziegler thrives. He's had the highest downward movement in baseball each year since 2011, and he was second in both 2009 and '10, but even that doesn't tell the full story -- of the 578 pitchers who have made 3,000 pitches since 2007, he's one of only seven to average downward movement. (He's the leader, of course.)
Really, that otherworldly movement, the kind that dives on the hitter but isn't fast enough to really get them to miss entirely, is what sets him apart. Due to that, Ziegler managed to find himself both as one of just five pitchers to get 30 saves with a strikeout percentage below 14% since 2000 (Danny Graves and Todd Jones did it multiple times), and also as the foremost groundballer of the century: 
Top GB/FB ratios, 2002-15 (of 1,921 qualified seasons)

1. Ziegler, 2015 -- 9.87
   
2. Zach Britton, 2015 -- 8.33
   
3. Ziegler, 2013 -- 6.55
   
4. Britton, 2014 -- 6.35
   (He's seventh and 11th on that list, too.)
   Needless to say, there aren't closers like Ziegler because there just aren't pitchers like Ziegler. Put another way, we have 153 closer seasons with 30 saves since 2007. The non-Ziegler pitchers averaged 93.6 mph on their fastball. Ziegler's 84.6 mph, as you'd expect, more than pulls up the rear. After all, he throws his sinking fastball 6 mph more softly than Jake Arrieta throws his changeup, which makes sense since he spins it more like a curve. Given baseball's preference for velocity and whiffs in the ninth, it's not really standard operating procedure.
   Then again, nothing about Ziegler's career has been standard, from the delivery to the record 38 consecutive scoreless innings to begin his career in 2008. Why should this be any different?